diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index d04a5be..0976b75 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -21,6 +21,7 @@
 import static android.net.NetworkRequest.Type.LISTEN;
 import static android.net.NetworkRequest.Type.REQUEST;
 import static android.net.NetworkRequest.Type.TRACK_DEFAULT;
+import static android.net.NetworkRequest.Type.TRACK_SYSTEM_DEFAULT;
 import static android.net.QosCallback.QosCallbackRegistrationException;
 
 import android.annotation.CallbackExecutor;
@@ -3721,7 +3722,8 @@
         printStackTrace();
         checkCallbackNotNull(callback);
         Preconditions.checkArgument(
-                reqType == TRACK_DEFAULT || need != null, "null NetworkCapabilities");
+                reqType == TRACK_DEFAULT || reqType == TRACK_SYSTEM_DEFAULT || need != null,
+                "null NetworkCapabilities");
         final NetworkRequest request;
         final String callingPackageName = mContext.getOpPackageName();
         try {
@@ -4192,8 +4194,9 @@
     }
 
     /**
-     * Registers to receive notifications about changes in the system default network. The callbacks
-     * will continue to be called until either the application exits or
+     * Registers to receive notifications about changes in the application's default network. This
+     * may be a physical network or a virtual network, such as a VPN that applies to the
+     * application. The callbacks will continue to be called until either the application exits or
      * {@link #unregisterNetworkCallback(NetworkCallback)} is called.
      *
      * <p>To avoid performance issues due to apps leaking callbacks, the system will limit the
@@ -4206,7 +4209,7 @@
      * {@link #unregisterNetworkCallback(NetworkCallback)}.
      *
      * @param networkCallback The {@link NetworkCallback} that the system will call as the
-     *                        system default network changes.
+     *                        application's default network changes.
      *                        The callback is invoked on the default internal Handler.
      * @throws RuntimeException if the app already has too many callbacks registered.
      */
@@ -4216,10 +4219,46 @@
     }
 
     /**
+     * Registers to receive notifications about changes in the application's default network. This
+     * may be a physical network or a virtual network, such as a VPN that applies to the
+     * application. The callbacks will continue to be called until either the application exits or
+     * {@link #unregisterNetworkCallback(NetworkCallback)} is called.
+     *
+     * <p>To avoid performance issues due to apps leaking callbacks, the system will limit the
+     * number of outstanding requests to 100 per app (identified by their UID), shared with
+     * all variants of this method, of {@link #requestNetwork} as well as
+     * {@link ConnectivityDiagnosticsManager#registerConnectivityDiagnosticsCallback}.
+     * Requesting a network with this method will count toward this limit. If this limit is
+     * exceeded, an exception will be thrown. To avoid hitting this issue and to conserve resources,
+     * make sure to unregister the callbacks with
+     * {@link #unregisterNetworkCallback(NetworkCallback)}.
+     *
+     * @param networkCallback The {@link NetworkCallback} that the system will call as the
+     *                        application's default network changes.
+     * @param handler {@link Handler} to specify the thread upon which the callback will be invoked.
+     * @throws RuntimeException if the app already has too many callbacks registered.
+     */
+    @RequiresPermission(android.Manifest.permission.ACCESS_NETWORK_STATE)
+    public void registerDefaultNetworkCallback(@NonNull NetworkCallback networkCallback,
+            @NonNull Handler handler) {
+        CallbackHandler cbHandler = new CallbackHandler(handler);
+        sendRequestForNetwork(null /* NetworkCapabilities need */, networkCallback, 0,
+                TRACK_DEFAULT, TYPE_NONE, cbHandler);
+    }
+
+    /**
      * Registers to receive notifications about changes in the system default network. The callbacks
      * will continue to be called until either the application exits or
      * {@link #unregisterNetworkCallback(NetworkCallback)} is called.
      *
+     * This method should not be used to determine networking state seen by applications, because in
+     * many cases, most or even all application traffic may not use the default network directly,
+     * and traffic from different applications may go on different networks by default. As an
+     * example, if a VPN is connected, traffic from all applications might be sent through the VPN
+     * and not onto the system default network. Applications or system components desiring to do
+     * determine network state as seen by applications should use other methods such as
+     * {@link #registerDefaultNetworkCallback(NetworkCallback, Handler)}.
+     *
      * <p>To avoid performance issues due to apps leaking callbacks, the system will limit the
      * number of outstanding requests to 100 per app (identified by their UID), shared with
      * all variants of this method, of {@link #requestNetwork} as well as
@@ -4233,20 +4272,19 @@
      *                        system default network changes.
      * @param handler {@link Handler} to specify the thread upon which the callback will be invoked.
      * @throws RuntimeException if the app already has too many callbacks registered.
+     *
+     * @hide
      */
-    @RequiresPermission(android.Manifest.permission.ACCESS_NETWORK_STATE)
-    public void registerDefaultNetworkCallback(@NonNull NetworkCallback networkCallback,
+    @SystemApi(client = MODULE_LIBRARIES)
+    @SuppressLint({"ExecutorRegistration", "PairedRegistration"})
+    @RequiresPermission(anyOf = {
+            NetworkStack.PERMISSION_MAINLINE_NETWORK_STACK,
+            android.Manifest.permission.NETWORK_SETTINGS})
+    public void registerSystemDefaultNetworkCallback(@NonNull NetworkCallback networkCallback,
             @NonNull Handler handler) {
-        // This works because if the NetworkCapabilities are null,
-        // ConnectivityService takes them from the default request.
-        //
-        // Since the capabilities are exactly the same as the default request's
-        // capabilities, this request is guaranteed, at all times, to be
-        // satisfied by the same network, if any, that satisfies the default
-        // request, i.e., the system default network.
         CallbackHandler cbHandler = new CallbackHandler(handler);
         sendRequestForNetwork(null /* NetworkCapabilities need */, networkCallback, 0,
-                TRACK_DEFAULT, TYPE_NONE, cbHandler);
+                TRACK_SYSTEM_DEFAULT, TYPE_NONE, cbHandler);
     }
 
     /**
diff --git a/framework/src/android/net/NetworkCapabilities.java b/framework/src/android/net/NetworkCapabilities.java
index 55b2c3c..9d67f0b 100644
--- a/framework/src/android/net/NetworkCapabilities.java
+++ b/framework/src/android/net/NetworkCapabilities.java
@@ -762,12 +762,14 @@
         final int originalSignalStrength = mSignalStrength;
         final int originalOwnerUid = getOwnerUid();
         final int[] originalAdministratorUids = getAdministratorUids();
+        final TransportInfo originalTransportInfo = getTransportInfo();
         clearAll();
         mTransportTypes = (originalTransportTypes & TEST_NETWORKS_ALLOWED_TRANSPORTS)
                 | (1 << TRANSPORT_TEST);
         mNetworkCapabilities = originalCapabilities & TEST_NETWORKS_ALLOWED_CAPABILITIES;
         mNetworkSpecifier = originalSpecifier;
         mSignalStrength = originalSignalStrength;
+        mTransportInfo = originalTransportInfo;
 
         // Only retain the owner and administrator UIDs if they match the app registering the remote
         // caller that registered the network.
diff --git a/framework/src/android/net/NetworkRequest.java b/framework/src/android/net/NetworkRequest.java
index 6540397..b4a651c 100644
--- a/framework/src/android/net/NetworkRequest.java
+++ b/framework/src/android/net/NetworkRequest.java
@@ -104,17 +104,14 @@
      *       callbacks about the single, highest scoring current network
      *       (if any) that matches the specified NetworkCapabilities, or
      *
-     *     - TRACK_DEFAULT, a hybrid of the two designed such that the
-     *       framework will issue callbacks for the single, highest scoring
-     *       current network (if any) that matches the capabilities of the
-     *       default Internet request (mDefaultRequest), but which cannot cause
-     *       the framework to either create or retain the existence of any
-     *       specific network. Note that from the point of view of the request
-     *       matching code, TRACK_DEFAULT is identical to REQUEST: its special
-     *       behaviour is not due to different semantics, but to the fact that
-     *       the system will only ever create a TRACK_DEFAULT with capabilities
-     *       that are identical to the default request's capabilities, thus
-     *       causing it to share fate in every way with the default request.
+     *     - TRACK_DEFAULT, which causes the framework to issue callbacks for
+     *       the single, highest scoring current network (if any) that will
+     *       be chosen for an app, but which cannot cause the framework to
+     *       either create or retain the existence of any specific network.
+     *
+     *     - TRACK_SYSTEM_DEFAULT, which causes the framework to send callbacks
+     *       for the network (if any) that satisfies the default Internet
+     *       request.
      *
      *     - BACKGROUND_REQUEST, like REQUEST but does not cause any networks
      *       to retain the NET_CAPABILITY_FOREGROUND capability. A network with
@@ -137,6 +134,7 @@
         TRACK_DEFAULT,
         REQUEST,
         BACKGROUND_REQUEST,
+        TRACK_SYSTEM_DEFAULT,
     };
 
     /**
@@ -601,6 +599,8 @@
                 return NetworkRequestProto.TYPE_REQUEST;
             case BACKGROUND_REQUEST:
                 return NetworkRequestProto.TYPE_BACKGROUND_REQUEST;
+            case TRACK_SYSTEM_DEFAULT:
+                return NetworkRequestProto.TYPE_TRACK_SYSTEM_DEFAULT;
             default:
                 return NetworkRequestProto.TYPE_UNKNOWN;
         }
diff --git a/framework/src/android/net/VpnManager.java b/framework/src/android/net/VpnManager.java
index 1812509..1e30283 100644
--- a/framework/src/android/net/VpnManager.java
+++ b/framework/src/android/net/VpnManager.java
@@ -55,13 +55,29 @@
 public class VpnManager {
     /** Type representing a lack of VPN @hide */
     public static final int TYPE_VPN_NONE = -1;
-    /** VPN service type code @hide */
+
+    /**
+     * A VPN created by an app using the {@link VpnService} API.
+     * @hide
+     */
     public static final int TYPE_VPN_SERVICE = 1;
-    /** Platform VPN type code @hide */
+
+    /**
+     * A VPN created using a {@link VpnManager} API such as {@link #startProvisionedVpnProfile}.
+     * @hide
+     */
     public static final int TYPE_VPN_PLATFORM = 2;
 
+    /**
+     * An IPsec VPN created by the built-in LegacyVpnRunner.
+     * @deprecated new Android devices should use VPN_TYPE_PLATFORM instead.
+     * @hide
+     */
+    @Deprecated
+    public static final int TYPE_VPN_LEGACY = 3;
+
     /** @hide */
-    @IntDef(value = {TYPE_VPN_NONE, TYPE_VPN_SERVICE, TYPE_VPN_PLATFORM})
+    @IntDef(value = {TYPE_VPN_NONE, TYPE_VPN_SERVICE, TYPE_VPN_PLATFORM, TYPE_VPN_LEGACY})
     @Retention(RetentionPolicy.SOURCE)
     public @interface VpnType {}