diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index 495c9d7..e4ce615 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -33,6 +33,7 @@
         "NetworkStackApiStableShims",
         "androidx.annotation_annotation",
         "modules-utils-build",
+        "modules-utils-statemachine",
         "networkstack-client",
         "android.hardware.tetheroffload.config-V1.0-java",
         "android.hardware.tetheroffload.control-V1.0-java",
@@ -41,7 +42,6 @@
         "net-utils-device-common",
         "net-utils-device-common-netlink",
         "netd-client",
-        "NetworkStackApiCurrentShims",
     ],
     libs: [
         "framework-connectivity",
diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index 69bb71f..9e6e34e 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -37,6 +37,7 @@
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.lang.ref.WeakReference;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -265,7 +266,7 @@
     public TetheringManager(@NonNull final Context context,
             @NonNull Supplier<IBinder> connectorSupplier) {
         mContext = context;
-        mCallback = new TetheringCallbackInternal();
+        mCallback = new TetheringCallbackInternal(this);
         mConnectorSupplier = connectorSupplier;
 
         final String pkgName = mContext.getOpPackageName();
@@ -289,6 +290,23 @@
         getConnector(c -> c.registerTetheringEventCallback(mCallback, pkgName));
     }
 
+    /** @hide */
+    @Override
+    protected void finalize() throws Throwable {
+        final String pkgName = mContext.getOpPackageName();
+        Log.i(TAG, "unregisterTetheringEventCallback:" + pkgName);
+        // 1. It's generally not recommended to perform long operations in finalize, but while
+        // unregisterTetheringEventCallback does an IPC, it's a oneway IPC so should not block.
+        // 2. If the connector is not yet connected, TetheringManager is impossible to finalize
+        // because the connector polling thread strong reference the TetheringManager object. So
+        // it's guaranteed that registerTetheringEventCallback was already called before calling
+        // unregisterTetheringEventCallback in finalize.
+        if (mConnector == null) Log.wtf(TAG, "null connector in finalize!");
+        getConnector(c -> c.unregisterTetheringEventCallback(mCallback, pkgName));
+
+        super.finalize();
+    }
+
     private void startPollingForConnector() {
         new Thread(() -> {
             while (true) {
@@ -415,7 +433,7 @@
         }
     }
 
-    private void throwIfPermissionFailure(final int errorCode) {
+    private static void throwIfPermissionFailure(final int errorCode) {
         switch (errorCode) {
             case TETHER_ERROR_NO_CHANGE_TETHERING_PERMISSION:
                 throw new SecurityException("No android.permission.TETHER_PRIVILEGED"
@@ -426,21 +444,40 @@
         }
     }
 
-    private class TetheringCallbackInternal extends ITetheringEventCallback.Stub {
+    private static class TetheringCallbackInternal extends ITetheringEventCallback.Stub {
         private volatile int mError = TETHER_ERROR_NO_ERROR;
         private final ConditionVariable mWaitForCallback = new ConditionVariable();
+        // This object is never garbage collected because the Tethering code running in
+        // the system server always maintains a reference to it for as long as
+        // mCallback is registered.
+        //
+        // Don't keep a strong reference to TetheringManager because otherwise
+        // TetheringManager cannot be garbage collected, and because TetheringManager
+        // stores the Context that it was created from, this will prevent the calling
+        // Activity from being garbage collected as well.
+        private final WeakReference<TetheringManager> mTetheringMgrRef;
+
+        TetheringCallbackInternal(final TetheringManager tm) {
+            mTetheringMgrRef = new WeakReference<>(tm);
+        }
 
         @Override
         public void onCallbackStarted(TetheringCallbackStartedParcel parcel) {
-            mTetheringConfiguration = parcel.config;
-            mTetherStatesParcel = parcel.states;
-            mWaitForCallback.open();
+            TetheringManager tetheringMgr = mTetheringMgrRef.get();
+            if (tetheringMgr != null) {
+                tetheringMgr.mTetheringConfiguration = parcel.config;
+                tetheringMgr.mTetherStatesParcel = parcel.states;
+                mWaitForCallback.open();
+            }
         }
 
         @Override
         public void onCallbackStopped(int errorCode) {
-            mError = errorCode;
-            mWaitForCallback.open();
+            TetheringManager tetheringMgr = mTetheringMgrRef.get();
+            if (tetheringMgr != null) {
+                mError = errorCode;
+                mWaitForCallback.open();
+            }
         }
 
         @Override
@@ -448,12 +485,14 @@
 
         @Override
         public void onConfigurationChanged(TetheringConfigurationParcel config) {
-            mTetheringConfiguration = config;
+            TetheringManager tetheringMgr = mTetheringMgrRef.get();
+            if (tetheringMgr != null) tetheringMgr.mTetheringConfiguration = config;
         }
 
         @Override
         public void onTetherStatesChanged(TetherStatesParcel states) {
-            mTetherStatesParcel = states;
+            TetheringManager tetheringMgr = mTetheringMgrRef.get();
+            if (tetheringMgr != null) tetheringMgr.mTetherStatesParcel = states;
         }
 
         @Override
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
index 4865e03..3c07580 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/MockTetheringService.java
@@ -22,7 +22,6 @@
 
 import android.content.Context;
 import android.content.Intent;
-import android.net.ITetheringConnector;
 import android.os.Binder;
 import android.os.IBinder;
 import android.util.ArrayMap;
@@ -72,8 +71,8 @@
             mBase = base;
         }
 
-        public ITetheringConnector getTetheringConnector() {
-            return ITetheringConnector.Stub.asInterface(mBase);
+        public IBinder getIBinder() {
+            return mBase;
         }
 
         public MockTetheringService getService() {
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
index 1b52f6e..f664d5d 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringServiceTest.java
@@ -26,6 +26,9 @@
 import static android.net.TetheringManager.TETHER_ERROR_NO_ERROR;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.eq;
@@ -40,10 +43,13 @@
 import android.net.IIntResultListener;
 import android.net.ITetheringConnector;
 import android.net.ITetheringEventCallback;
+import android.net.TetheringManager;
 import android.net.TetheringRequestParcel;
 import android.net.ip.IpServer;
 import android.os.Bundle;
+import android.os.ConditionVariable;
 import android.os.Handler;
+import android.os.IBinder;
 import android.os.ResultReceiver;
 
 import androidx.test.InstrumentationRegistry;
@@ -62,6 +68,10 @@
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
+import java.lang.ref.WeakReference;
+import java.util.ArrayList;
+import java.util.function.Supplier;
+
 @RunWith(AndroidJUnit4.class)
 @SmallTest
 public final class TetheringServiceTest {
@@ -113,7 +123,7 @@
                 InstrumentationRegistry.getTargetContext(),
                 MockTetheringService.class);
         mMockConnector = (MockTetheringConnector) mServiceTestRule.bindService(mMockServiceIntent);
-        mTetheringConnector = mMockConnector.getTetheringConnector();
+        mTetheringConnector = ITetheringConnector.Stub.asInterface(mMockConnector.getIBinder());
         final MockTetheringService service = mMockConnector.getService();
         mTethering = service.getTethering();
     }
@@ -493,4 +503,81 @@
             verifyNoMoreInteractionsForTethering();
         });
     }
+
+    private class ConnectorSupplier<T> implements Supplier<T> {
+        private T mResult = null;
+
+        public void set(T result) {
+            mResult = result;
+        }
+
+        @Override
+        public T get() {
+            return mResult;
+        }
+    }
+
+    private void forceGc() {
+        System.gc();
+        System.runFinalization();
+        System.gc();
+    }
+
+    @Test
+    public void testTetheringManagerLeak() throws Exception {
+        runAsAccessNetworkState((none) -> {
+            final ArrayList<ITetheringEventCallback> callbacks = new ArrayList<>();
+            final ConditionVariable registeredCv = new ConditionVariable(false);
+            doAnswer((invocation) -> {
+                final Object[] args = invocation.getArguments();
+                callbacks.add((ITetheringEventCallback) args[0]);
+                registeredCv.open();
+                return null;
+            }).when(mTethering).registerTetheringEventCallback(any());
+
+            doAnswer((invocation) -> {
+                final Object[] args = invocation.getArguments();
+                callbacks.remove((ITetheringEventCallback) args[0]);
+                return null;
+            }).when(mTethering).unregisterTetheringEventCallback(any());
+
+            final ConnectorSupplier<IBinder> supplier = new ConnectorSupplier<>();
+
+            TetheringManager tm = new TetheringManager(mMockConnector.getService(), supplier);
+            assertNotNull(tm);
+            assertEquals("Internal callback should not be registered", 0, callbacks.size());
+
+            final WeakReference<TetheringManager> weakTm = new WeakReference(tm);
+            assertNotNull(weakTm.get());
+
+            // TetheringManager couldn't be GCed because pollingConnector thread implicitly
+            // reference TetheringManager object.
+            tm = null;
+            forceGc();
+            assertNotNull(weakTm.get());
+
+            // After getting connector, pollingConnector thread stops and internal callback is
+            // registered.
+            supplier.set(mMockConnector.getIBinder());
+            final long timeout = 500L;
+            if (!registeredCv.block(timeout)) {
+                fail("TetheringManager poll connector fail after " + timeout + " ms");
+            }
+            assertEquals("Internal callback is not registered", 1, callbacks.size());
+            assertNotNull(weakTm.get());
+
+            final int attempts = 100;
+            final long waitIntervalMs = 50;
+            for (int i = 0; i < attempts; i++) {
+                forceGc();
+                if (weakTm.get() == null) break;
+
+                Thread.sleep(waitIntervalMs);
+            }
+            assertNull("TetheringManager weak reference still not null after " + attempts
+                    + " attempts", weakTm.get());
+
+            assertEquals("Internal callback is not unregistered", 0, callbacks.size());
+        });
+    }
 }
diff --git a/framework/src/android/net/NetworkCapabilities.java b/framework/src/android/net/NetworkCapabilities.java
index 4a86873..75f0129 100644
--- a/framework/src/android/net/NetworkCapabilities.java
+++ b/framework/src/android/net/NetworkCapabilities.java
@@ -2128,14 +2128,17 @@
             sb.append(" SubscriptionIds: ").append(mSubIds);
         }
 
-        if (mUnderlyingNetworks != null && mUnderlyingNetworks.size() > 0) {
-            sb.append(" Underlying networks: [");
+        sb.append(" UnderlyingNetworks: ");
+        if (mUnderlyingNetworks != null) {
+            sb.append("[");
             final StringJoiner joiner = new StringJoiner(",");
             for (int i = 0; i < mUnderlyingNetworks.size(); i++) {
                 joiner.add(mUnderlyingNetworks.get(i).toString());
             }
             sb.append(joiner.toString());
             sb.append("]");
+        } else {
+            sb.append("Null");
         }
 
         sb.append("]");
diff --git a/framework/src/android/net/NetworkInfo.java b/framework/src/android/net/NetworkInfo.java
index bb23494..433933f 100644
--- a/framework/src/android/net/NetworkInfo.java
+++ b/framework/src/android/net/NetworkInfo.java
@@ -179,21 +179,19 @@
 
     /** {@hide} */
     @UnsupportedAppUsage
-    public NetworkInfo(NetworkInfo source) {
-        if (source != null) {
-            synchronized (source) {
-                mNetworkType = source.mNetworkType;
-                mSubtype = source.mSubtype;
-                mTypeName = source.mTypeName;
-                mSubtypeName = source.mSubtypeName;
-                mState = source.mState;
-                mDetailedState = source.mDetailedState;
-                mReason = source.mReason;
-                mExtraInfo = source.mExtraInfo;
-                mIsFailover = source.mIsFailover;
-                mIsAvailable = source.mIsAvailable;
-                mIsRoaming = source.mIsRoaming;
-            }
+    public NetworkInfo(@NonNull NetworkInfo source) {
+        synchronized (source) {
+            mNetworkType = source.mNetworkType;
+            mSubtype = source.mSubtype;
+            mTypeName = source.mTypeName;
+            mSubtypeName = source.mSubtypeName;
+            mState = source.mState;
+            mDetailedState = source.mDetailedState;
+            mReason = source.mReason;
+            mExtraInfo = source.mExtraInfo;
+            mIsFailover = source.mIsFailover;
+            mIsAvailable = source.mIsAvailable;
+            mIsRoaming = source.mIsRoaming;
         }
     }
 
@@ -479,7 +477,7 @@
      * @param detailedState the {@link DetailedState}.
      * @param reason a {@code String} indicating the reason for the state change,
      * if one was supplied. May be {@code null}.
-     * @param extraInfo an optional {@code String} providing addditional network state
+     * @param extraInfo an optional {@code String} providing additional network state
      * information passed up from the lower networking layers.
      * @deprecated Use {@link NetworkCapabilities} instead.
      */
@@ -491,6 +489,11 @@
             this.mState = stateMap.get(detailedState);
             this.mReason = reason;
             this.mExtraInfo = extraInfo;
+            // Catch both the case where detailedState is null and the case where it's some
+            // unknown value
+            if (null == mState) {
+                throw new NullPointerException("Unknown DetailedState : " + detailedState);
+            }
         }
     }
 
diff --git a/service/Android.bp b/service/Android.bp
index 911d67f..3ff7a7c 100644
--- a/service/Android.bp
+++ b/service/Android.bp
@@ -67,7 +67,8 @@
     static_libs: [
         "dnsresolver_aidl_interface-V9-java",
         "modules-utils-build",
-        "modules-utils-os",
+        "modules-utils-shell-command-handler",
+        "modules-utils-statemachine",
         "net-utils-device-common",
         "net-utils-device-common-netlink",
         "net-utils-framework-common",
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 408dba3..88cd876 100644
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -2032,6 +2032,7 @@
         if (!checkSettingsPermission(callerPid, callerUid)) {
             newNc.setUids(null);
             newNc.setSSID(null);
+            newNc.setUnderlyingNetworks(null);
         }
         if (newNc.getNetworkSpecifier() != null) {
             newNc.setNetworkSpecifier(newNc.getNetworkSpecifier().redact());
@@ -7305,7 +7306,9 @@
         boolean suspended = true; // suspended if all underlying are suspended
 
         boolean hadUnderlyingNetworks = false;
+        ArrayList<Network> newUnderlyingNetworks = null;
         if (null != underlyingNetworks) {
+            newUnderlyingNetworks = new ArrayList<>();
             for (Network underlyingNetwork : underlyingNetworks) {
                 final NetworkAgentInfo underlying =
                         getNetworkAgentInfoForNetwork(underlyingNetwork);
@@ -7335,6 +7338,7 @@
                 // If this network is not suspended, the VPN is not suspended (the VPN
                 // is able to transfer some data).
                 suspended &= !underlyingCaps.hasCapability(NET_CAPABILITY_NOT_SUSPENDED);
+                newUnderlyingNetworks.add(underlyingNetwork);
             }
         }
         if (!hadUnderlyingNetworks) {
@@ -7352,6 +7356,7 @@
         newNc.setCapability(NET_CAPABILITY_NOT_ROAMING, !roaming);
         newNc.setCapability(NET_CAPABILITY_NOT_CONGESTED, !congested);
         newNc.setCapability(NET_CAPABILITY_NOT_SUSPENDED, !suspended);
+        newNc.setUnderlyingNetworks(newUnderlyingNetworks);
     }
 
     /**
diff --git a/service/src/com/android/server/connectivity/NetworkAgentInfo.java b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
index 6426f86..b7f3ed9 100644
--- a/service/src/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/service/src/com/android/server/connectivity/NetworkAgentInfo.java
@@ -377,6 +377,9 @@
         this.creatorUid = creatorUid;
         mLingerDurationMs = lingerDurationMs;
         mQosCallbackTracker = qosCallbackTracker;
+        declaredUnderlyingNetworks = (nc.getUnderlyingNetworks() != null)
+                ? nc.getUnderlyingNetworks().toArray(new Network[0])
+                : null;
     }
 
     private class AgentDeathMonitor implements IBinder.DeathRecipient {
diff --git a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
index 4329a83..594000b 100644
--- a/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
+++ b/tests/cts/net/src/android/net/cts/ConnectivityManagerTest.java
@@ -714,6 +714,12 @@
                 .build();
     }
 
+    private boolean hasPrivateDnsValidated(CallbackEntry entry, Network networkForPrivateDns) {
+        if (!networkForPrivateDns.equals(entry.getNetwork())) return false;
+        final NetworkCapabilities nc = ((CallbackEntry.CapabilitiesChanged) entry).getCaps();
+        return !nc.isPrivateDnsBroken() && nc.hasCapability(NET_CAPABILITY_VALIDATED);
+    }
+
     @AppModeFull(reason = "WRITE_SECURE_SETTINGS permission can't be granted to instant apps")
     @Test @IgnoreUpTo(Build.VERSION_CODES.Q)
     public void testIsPrivateDnsBroken() throws InterruptedException {
@@ -727,8 +733,7 @@
             mCtsNetUtils.setPrivateDnsStrictMode(goodPrivateDnsServer);
             final Network networkForPrivateDns =  mCtsNetUtils.ensureWifiConnected();
             cb.eventuallyExpect(CallbackEntry.NETWORK_CAPS_UPDATED, NETWORK_CALLBACK_TIMEOUT_MS,
-                    entry -> (!((CallbackEntry.CapabilitiesChanged) entry).getCaps()
-                    .isPrivateDnsBroken()) && networkForPrivateDns.equals(entry.getNetwork()));
+                    entry -> hasPrivateDnsValidated(entry, networkForPrivateDns));
 
             // Verifying the broken private DNS sever
             mCtsNetUtils.setPrivateDnsStrictMode(invalidPrivateDnsServer);
@@ -1183,6 +1188,7 @@
     @AppModeFull(reason = "Cannot get WifiManager in instant app mode")
     @Test
     public void testGetMultipathPreference() throws Exception {
+        assumeTrue(mPackageManager.hasSystemFeature(FEATURE_WIFI));
         final ContentResolver resolver = mContext.getContentResolver();
         mCtsNetUtils.ensureWifiConnected();
         final String ssid = unquoteSSID(mWifiManager.getConnectionInfo().getSSID());
@@ -2828,6 +2834,19 @@
             });
     }
 
+    /**
+     *  The networks used in this test are real networks and as such they can see seemingly random
+     *  updates of their capabilities or link properties as conditions change, e.g. the network
+     *  loses validation or IPv4 shows up. Many tests should simply treat these callbacks as
+     *  spurious.
+     */
+    private void assertNoCallbackExceptCapOrLpChange(
+            @NonNull final TestableNetworkCallback cb) {
+        cb.assertNoCallbackThat(NO_CALLBACK_TIMEOUT_MS,
+                c -> !(c instanceof CallbackEntry.CapabilitiesChanged
+                        || c instanceof CallbackEntry.LinkPropertiesChanged));
+    }
+
     @AppModeFull(reason = "Cannot get WifiManager in instant app mode")
     @Test
     public void testMobileDataPreferredUids() throws Exception {
@@ -2860,8 +2879,7 @@
             // CtsNetTestCases uid is not listed in MOBILE_DATA_PREFERRED_UIDS setting, so the
             // per-app default network should be same as system default network.
             waitForAvailable(systemDefaultCb, wifiNetwork);
-            defaultTrackingCb.eventuallyExpect(CallbackEntry.AVAILABLE, NETWORK_CALLBACK_TIMEOUT_MS,
-                    entry -> wifiNetwork.equals(entry.getNetwork()));
+            waitForAvailable(defaultTrackingCb, wifiNetwork);
             // Active network for CtsNetTestCases uid should be wifi now.
             assertEquals(wifiNetwork, mCm.getActiveNetwork());
 
@@ -2871,10 +2889,10 @@
             newMobileDataPreferredUids.add(uid);
             ConnectivitySettingsManager.setMobileDataPreferredUids(
                     mContext, newMobileDataPreferredUids);
-            defaultTrackingCb.eventuallyExpect(CallbackEntry.AVAILABLE, NETWORK_CALLBACK_TIMEOUT_MS,
-                    entry -> cellNetwork.equals(entry.getNetwork()));
-            // System default network doesn't change.
-            systemDefaultCb.assertNoCallback();
+            waitForAvailable(defaultTrackingCb, cellNetwork);
+            // No change for system default network. Expect no callback except CapabilitiesChanged
+            // or LinkPropertiesChanged which may be triggered randomly from wifi network.
+            assertNoCallbackExceptCapOrLpChange(systemDefaultCb);
             // Active network for CtsNetTestCases uid should change to cell, too.
             assertEquals(cellNetwork, mCm.getActiveNetwork());
 
@@ -2883,10 +2901,10 @@
             newMobileDataPreferredUids.remove(uid);
             ConnectivitySettingsManager.setMobileDataPreferredUids(
                     mContext, newMobileDataPreferredUids);
-            defaultTrackingCb.eventuallyExpect(CallbackEntry.AVAILABLE, NETWORK_CALLBACK_TIMEOUT_MS,
-                    entry -> wifiNetwork.equals(entry.getNetwork()));
-            // System default network still doesn't change.
-            systemDefaultCb.assertNoCallback();
+            waitForAvailable(defaultTrackingCb, wifiNetwork);
+            // No change for system default network. Expect no callback except CapabilitiesChanged
+            // or LinkPropertiesChanged which may be triggered randomly from wifi network.
+            assertNoCallbackExceptCapOrLpChange(systemDefaultCb);
             // Active network for CtsNetTestCases uid should change back to wifi.
             assertEquals(wifiNetwork, mCm.getActiveNetwork());
         } finally {
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index 352a468..c54a11e 100644
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -151,6 +151,7 @@
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeTrue;
 import static org.mockito.AdditionalMatchers.aryEq;
 import static org.mockito.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.anyLong;
@@ -319,6 +320,7 @@
 import com.android.internal.util.WakeupMessage;
 import com.android.internal.util.test.BroadcastInterceptingContext;
 import com.android.internal.util.test.FakeSettingsProvider;
+import com.android.modules.utils.build.SdkLevel;
 import com.android.net.module.util.ArrayTrackRecord;
 import com.android.net.module.util.CollectionUtils;
 import com.android.net.module.util.LocationPermissionChecker;
@@ -7252,6 +7254,15 @@
         initialCaps.addTransportType(TRANSPORT_VPN);
         initialCaps.addCapability(NET_CAPABILITY_INTERNET);
         initialCaps.removeCapability(NET_CAPABILITY_NOT_VPN);
+        final ArrayList<Network> emptyUnderlyingNetworks = new ArrayList<Network>();
+        final ArrayList<Network> underlyingNetworksContainMobile = new ArrayList<Network>();
+        underlyingNetworksContainMobile.add(mobile);
+        final ArrayList<Network> underlyingNetworksContainWifi = new ArrayList<Network>();
+        underlyingNetworksContainWifi.add(wifi);
+        final ArrayList<Network> underlyingNetworksContainMobileAndMobile =
+                new ArrayList<Network>();
+        underlyingNetworksContainMobileAndMobile.add(mobile);
+        underlyingNetworksContainMobileAndMobile.add(wifi);
 
         final NetworkCapabilities withNoUnderlying = new NetworkCapabilities();
         withNoUnderlying.addCapability(NET_CAPABILITY_INTERNET);
@@ -7260,17 +7271,20 @@
         withNoUnderlying.addCapability(NET_CAPABILITY_NOT_SUSPENDED);
         withNoUnderlying.addTransportType(TRANSPORT_VPN);
         withNoUnderlying.removeCapability(NET_CAPABILITY_NOT_VPN);
+        withNoUnderlying.setUnderlyingNetworks(emptyUnderlyingNetworks);
 
         final NetworkCapabilities withMobileUnderlying = new NetworkCapabilities(withNoUnderlying);
         withMobileUnderlying.addTransportType(TRANSPORT_CELLULAR);
         withMobileUnderlying.removeCapability(NET_CAPABILITY_NOT_ROAMING);
         withMobileUnderlying.removeCapability(NET_CAPABILITY_NOT_SUSPENDED);
         withMobileUnderlying.setLinkDownstreamBandwidthKbps(10);
+        withMobileUnderlying.setUnderlyingNetworks(underlyingNetworksContainMobile);
 
         final NetworkCapabilities withWifiUnderlying = new NetworkCapabilities(withNoUnderlying);
         withWifiUnderlying.addTransportType(TRANSPORT_WIFI);
         withWifiUnderlying.addCapability(NET_CAPABILITY_NOT_METERED);
         withWifiUnderlying.setLinkUpstreamBandwidthKbps(20);
+        withWifiUnderlying.setUnderlyingNetworks(underlyingNetworksContainWifi);
 
         final NetworkCapabilities withWifiAndMobileUnderlying =
                 new NetworkCapabilities(withNoUnderlying);
@@ -7280,6 +7294,7 @@
         withWifiAndMobileUnderlying.removeCapability(NET_CAPABILITY_NOT_ROAMING);
         withWifiAndMobileUnderlying.setLinkDownstreamBandwidthKbps(10);
         withWifiAndMobileUnderlying.setLinkUpstreamBandwidthKbps(20);
+        withWifiAndMobileUnderlying.setUnderlyingNetworks(underlyingNetworksContainMobileAndMobile);
 
         final NetworkCapabilities initialCapsNotMetered = new NetworkCapabilities(initialCaps);
         initialCapsNotMetered.addCapability(NET_CAPABILITY_NOT_METERED);
@@ -7287,40 +7302,61 @@
         NetworkCapabilities caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{}, initialCapsNotMetered, caps);
         assertEquals(withNoUnderlying, caps);
+        assertEquals(0, new ArrayList<>(caps.getUnderlyingNetworks()).size());
 
         caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{null}, initialCapsNotMetered, caps);
         assertEquals(withNoUnderlying, caps);
+        assertEquals(0, new ArrayList<>(caps.getUnderlyingNetworks()).size());
 
         caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{mobile}, initialCapsNotMetered, caps);
         assertEquals(withMobileUnderlying, caps);
+        assertEquals(1, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(mobile, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
 
+        caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{wifi}, initialCapsNotMetered, caps);
         assertEquals(withWifiUnderlying, caps);
+        assertEquals(1, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(wifi, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
 
         withWifiUnderlying.removeCapability(NET_CAPABILITY_NOT_METERED);
         caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{wifi}, initialCaps, caps);
         assertEquals(withWifiUnderlying, caps);
+        assertEquals(1, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(wifi, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
 
         caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{mobile, wifi}, initialCaps, caps);
         assertEquals(withWifiAndMobileUnderlying, caps);
+        assertEquals(2, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(mobile, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
+        assertEquals(wifi, new ArrayList<>(caps.getUnderlyingNetworks()).get(1));
 
         withWifiUnderlying.addCapability(NET_CAPABILITY_NOT_METERED);
         caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{null, mobile, null, wifi},
                 initialCapsNotMetered, caps);
         assertEquals(withWifiAndMobileUnderlying, caps);
+        assertEquals(2, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(mobile, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
+        assertEquals(wifi, new ArrayList<>(caps.getUnderlyingNetworks()).get(1));
 
         caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(new Network[]{null, mobile, null, wifi},
                 initialCapsNotMetered, caps);
         assertEquals(withWifiAndMobileUnderlying, caps);
+        assertEquals(2, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(mobile, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
+        assertEquals(wifi, new ArrayList<>(caps.getUnderlyingNetworks()).get(1));
 
+        caps = new NetworkCapabilities(initialCaps);
         mService.applyUnderlyingCapabilities(null, initialCapsNotMetered, caps);
         assertEquals(withWifiUnderlying, caps);
+        assertEquals(1, new ArrayList<>(caps.getUnderlyingNetworks()).size());
+        assertEquals(wifi, new ArrayList<>(caps.getUnderlyingNetworks()).get(0));
     }
 
     @Test
@@ -7329,51 +7365,78 @@
         final NetworkRequest request = new NetworkRequest.Builder()
                 .removeCapability(NET_CAPABILITY_NOT_VPN).build();
 
-        mCm.registerNetworkCallback(request, callback);
+        runAsShell(NETWORK_SETTINGS, () -> {
+            mCm.registerNetworkCallback(request, callback);
 
-        // Bring up a VPN that specifies an underlying network that does not exist yet.
-        // Note: it's sort of meaningless for a VPN app to declare a network that doesn't exist yet,
-        // (and doing so is difficult without using reflection) but it's good to test that the code
-        // behaves approximately correctly.
-        mMockVpn.establishForMyUid(false, true, false);
-        assertUidRangesUpdatedForMyUid(true);
-        final Network wifiNetwork = new Network(mNetIdManager.peekNextNetId());
-        mMockVpn.setUnderlyingNetworks(new Network[]{wifiNetwork});
-        callback.expectAvailableCallbacksUnvalidated(mMockVpn);
-        assertTrue(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
-                .hasTransport(TRANSPORT_VPN));
-        assertFalse(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
-                .hasTransport(TRANSPORT_WIFI));
+            // Bring up a VPN that specifies an underlying network that does not exist yet.
+            // Note: it's sort of meaningless for a VPN app to declare a network that doesn't exist
+            // yet, (and doing so is difficult without using reflection) but it's good to test that
+            // the code behaves approximately correctly.
+            mMockVpn.establishForMyUid(false, true, false);
+            callback.expectAvailableCallbacksUnvalidated(mMockVpn);
+            assertUidRangesUpdatedForMyUid(true);
+            final Network wifiNetwork = new Network(mNetIdManager.peekNextNetId());
+            mMockVpn.setUnderlyingNetworks(new Network[]{wifiNetwork});
+            // onCapabilitiesChanged() should be called because
+            // NetworkCapabilities#mUnderlyingNetworks is updated.
+            CallbackEntry ce = callback.expectCallback(CallbackEntry.NETWORK_CAPS_UPDATED,
+                    mMockVpn);
+            final NetworkCapabilities vpnNc1 = ((CallbackEntry.CapabilitiesChanged) ce).getCaps();
+            // Since the wifi network hasn't brought up,
+            // ConnectivityService#applyUnderlyingCapabilities cannot find it. Update
+            // NetworkCapabilities#mUnderlyingNetworks to an empty array, and it will be updated to
+            // the correct underlying networks once the wifi network brings up. But this case
+            // shouldn't happen in reality since no one could get the network which hasn't brought
+            // up. For the empty array of underlying networks, it should be happened for 2 cases,
+            // the first one is that the VPN app declares an empty array for its underlying
+            // networks, the second one is that the underlying networks are torn down.
+            //
+            // It shouldn't be null since the null value means the underlying networks of this
+            // network should follow the default network.
+            final ArrayList<Network> underlyingNetwork = new ArrayList<>();
+            assertEquals(underlyingNetwork, vpnNc1.getUnderlyingNetworks());
+            // Since the wifi network isn't exist, applyUnderlyingCapabilities()
+            assertTrue(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
+                    .hasTransport(TRANSPORT_VPN));
+            assertFalse(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
+                    .hasTransport(TRANSPORT_WIFI));
 
-        // Make that underlying network connect, and expect to see its capabilities immediately
-        // reflected in the VPN's capabilities.
-        mWiFiNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_WIFI);
-        assertEquals(wifiNetwork, mWiFiNetworkAgent.getNetwork());
-        mWiFiNetworkAgent.connect(false);
-        // TODO: the callback for the VPN happens before any callbacks are called for the wifi
-        // network that has just connected. There appear to be two issues here:
-        // 1. The VPN code will accept an underlying network as soon as getNetworkCapabilities() for
-        //    it returns non-null (which happens very early, during handleRegisterNetworkAgent).
-        //    This is not correct because that that point the network is not connected and cannot
-        //    pass any traffic.
-        // 2. When a network connects, updateNetworkInfo propagates underlying network capabilities
-        //    before rematching networks.
-        // Given that this scenario can't really happen, this is probably fine for now.
-        callback.expectCallback(CallbackEntry.NETWORK_CAPS_UPDATED, mMockVpn);
-        callback.expectAvailableCallbacksUnvalidated(mWiFiNetworkAgent);
-        assertTrue(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
-                .hasTransport(TRANSPORT_VPN));
-        assertTrue(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
-                .hasTransport(TRANSPORT_WIFI));
+            // Make that underlying network connect, and expect to see its capabilities immediately
+            // reflected in the VPN's capabilities.
+            mWiFiNetworkAgent = new TestNetworkAgentWrapper(TRANSPORT_WIFI);
+            assertEquals(wifiNetwork, mWiFiNetworkAgent.getNetwork());
+            mWiFiNetworkAgent.connect(false);
+            // TODO: the callback for the VPN happens before any callbacks are called for the wifi
+            // network that has just connected. There appear to be two issues here:
+            // 1. The VPN code will accept an underlying network as soon as getNetworkCapabilities()
+            //    for it returns non-null (which happens very early, during
+            //    handleRegisterNetworkAgent).
+            //    This is not correct because that that point the network is not connected and
+            //    cannot pass any traffic.
+            // 2. When a network connects, updateNetworkInfo propagates underlying network
+            //    capabilities before rematching networks.
+            // Given that this scenario can't really happen, this is probably fine for now.
+            ce = callback.expectCallback(CallbackEntry.NETWORK_CAPS_UPDATED, mMockVpn);
+            final NetworkCapabilities vpnNc2 = ((CallbackEntry.CapabilitiesChanged) ce).getCaps();
+            // The wifi network is brought up, NetworkCapabilities#mUnderlyingNetworks is updated to
+            // it.
+            underlyingNetwork.add(wifiNetwork);
+            assertEquals(underlyingNetwork, vpnNc2.getUnderlyingNetworks());
+            callback.expectAvailableCallbacksUnvalidated(mWiFiNetworkAgent);
+            assertTrue(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
+                    .hasTransport(TRANSPORT_VPN));
+            assertTrue(mCm.getNetworkCapabilities(mMockVpn.getNetwork())
+                    .hasTransport(TRANSPORT_WIFI));
 
-        // Disconnect the network, and expect to see the VPN capabilities change accordingly.
-        mWiFiNetworkAgent.disconnect();
-        callback.expectCallback(CallbackEntry.LOST, mWiFiNetworkAgent);
-        callback.expectCapabilitiesThat(mMockVpn, (nc) ->
-                nc.getTransportTypes().length == 1 && nc.hasTransport(TRANSPORT_VPN));
+            // Disconnect the network, and expect to see the VPN capabilities change accordingly.
+            mWiFiNetworkAgent.disconnect();
+            callback.expectCallback(CallbackEntry.LOST, mWiFiNetworkAgent);
+            callback.expectCapabilitiesThat(mMockVpn, (nc) ->
+                    nc.getTransportTypes().length == 1 && nc.hasTransport(TRANSPORT_VPN));
 
-        mMockVpn.disconnect();
-        mCm.unregisterNetworkCallback(callback);
+            mMockVpn.disconnect();
+            mCm.unregisterNetworkCallback(callback);
+        });
     }
 
     private void assertGetNetworkInfoOfGetActiveNetworkIsConnected(boolean expectedConnectivity) {
@@ -10697,6 +10760,14 @@
         return fakeNai(wifiNc, info);
     }
 
+    private NetworkAgentInfo fakeVpnNai(NetworkCapabilities nc) {
+        final NetworkCapabilities vpnNc = new NetworkCapabilities.Builder(nc)
+                .addTransportType(TRANSPORT_VPN).build();
+        final NetworkInfo info = new NetworkInfo(TYPE_VPN, 0 /* subtype */,
+                ConnectivityManager.getNetworkTypeName(TYPE_VPN), "" /* subtypeName */);
+        return fakeNai(vpnNc, info);
+    }
+
     private NetworkAgentInfo fakeNai(NetworkCapabilities nc, NetworkInfo networkInfo) {
         return new NetworkAgentInfo(null, new Network(NET_ID), networkInfo, new LinkProperties(),
                 nc, new NetworkScore.Builder().setLegacyInt(0).build(),
@@ -10831,6 +10902,36 @@
     }
 
     @Test
+    public void testUnderlyingNetworksWillBeSetInNetworkAgentInfoConstructor() throws Exception {
+        assumeTrue(SdkLevel.isAtLeastT());
+        final Network network1 = new Network(100);
+        final Network network2 = new Network(101);
+        final List<Network> underlyingNetworks = new ArrayList<>();
+        final NetworkCapabilities ncWithEmptyUnderlyingNetworks = new NetworkCapabilities.Builder()
+                .setUnderlyingNetworks(underlyingNetworks)
+                .build();
+        final NetworkAgentInfo vpnNaiWithEmptyUnderlyingNetworks =
+                fakeVpnNai(ncWithEmptyUnderlyingNetworks);
+        assertEquals(underlyingNetworks,
+                Arrays.asList(vpnNaiWithEmptyUnderlyingNetworks.declaredUnderlyingNetworks));
+
+        underlyingNetworks.add(network1);
+        underlyingNetworks.add(network2);
+        final NetworkCapabilities ncWithUnderlyingNetworks = new NetworkCapabilities.Builder()
+                .setUnderlyingNetworks(underlyingNetworks)
+                .build();
+        final NetworkAgentInfo vpnNaiWithUnderlyingNetwokrs = fakeVpnNai(ncWithUnderlyingNetworks);
+        assertEquals(underlyingNetworks,
+                Arrays.asList(vpnNaiWithUnderlyingNetwokrs.declaredUnderlyingNetworks));
+
+        final NetworkCapabilities ncWithoutUnderlyingNetworks = new NetworkCapabilities.Builder()
+                .build();
+        final NetworkAgentInfo vpnNaiWithoutUnderlyingNetwokrs =
+                fakeVpnNai(ncWithoutUnderlyingNetworks);
+        assertNull(vpnNaiWithoutUnderlyingNetwokrs.declaredUnderlyingNetworks);
+    }
+
+    @Test
     public void testRegisterConnectivityDiagnosticsCallbackCallsOnConnectivityReport()
             throws Exception {
         // Set up the Network, which leads to a ConnectivityReport being cached for the network.
diff --git a/tests/unit/java/com/android/server/connectivity/Nat464XlatTest.java b/tests/unit/java/com/android/server/connectivity/Nat464XlatTest.java
index f358726..aa4c4e3 100644
--- a/tests/unit/java/com/android/server/connectivity/Nat464XlatTest.java
+++ b/tests/unit/java/com/android/server/connectivity/Nat464XlatTest.java
@@ -109,8 +109,8 @@
 
         mNai.linkProperties = new LinkProperties();
         mNai.linkProperties.setInterfaceName(BASE_IFACE);
-        mNai.networkInfo = new NetworkInfo(null);
-        mNai.networkInfo.setType(ConnectivityManager.TYPE_WIFI);
+        mNai.networkInfo = new NetworkInfo(ConnectivityManager.TYPE_WIFI, 0 /* subtype */,
+                null /* typeName */, null /* subtypeName */);
         mNai.networkCapabilities = new NetworkCapabilities();
         markNetworkConnected();
         when(mNai.connService()).thenReturn(mConnectivity);