diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 44935fc..35a394d 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -1288,7 +1288,7 @@
 
             // Finally bring up serving on the new interface
             mWifiP2pTetherInterface = group.getInterface();
-            enableWifiIpServing(mWifiP2pTetherInterface, IFACE_IP_MODE_LOCAL_ONLY);
+            enableWifiP2pIpServing(mWifiP2pTetherInterface);
         }
 
         private void handleUserRestrictionAction() {
@@ -1379,20 +1379,22 @@
         changeInterfaceState(ifname, ipServingMode);
     }
 
-    private void disableWifiIpServingCommon(int tetheringType, String ifname, int apState) {
-        mLog.log("Canceling WiFi tethering request -"
-                + " type=" + tetheringType
-                + " interface=" + ifname
-                + " state=" + apState);
-
-        if (!TextUtils.isEmpty(ifname)) {
-            final TetherState ts = mTetherStates.get(ifname);
-            if (ts != null) {
-                ts.ipServer.unwanted();
-                return;
-            }
+    private void disableWifiIpServingCommon(int tetheringType, String ifname) {
+        if (!TextUtils.isEmpty(ifname) && mTetherStates.containsKey(ifname)) {
+            mTetherStates.get(ifname).ipServer.unwanted();
+            return;
         }
 
+        if (SdkLevel.isAtLeastT()) {
+            mLog.e("Tethering no longer handle untracked interface after T: " + ifname);
+            return;
+        }
+
+        // Attempt to guess the interface name before T. Pure AOSP code should never enter here
+        // because WIFI_AP_STATE_CHANGED intent always include ifname and it should be tracked
+        // by mTetherStates. In case OEMs have some modification in wifi side which pass null
+        // or empty ifname. Before T, tethering allow to disable the first wifi ipServer if
+        // given ifname don't match any tracking ipServer.
         for (int i = 0; i < mTetherStates.size(); i++) {
             final IpServer ipServer = mTetherStates.valueAt(i).ipServer;
             if (ipServer.interfaceType() == tetheringType) {
@@ -1400,7 +1402,6 @@
                 return;
             }
         }
-
         mLog.log("Error disabling Wi-Fi IP serving; "
                 + (TextUtils.isEmpty(ifname) ? "no interface name specified"
                                            : "specified interface: " + ifname));
@@ -1409,20 +1410,39 @@
     private void disableWifiIpServing(String ifname, int apState) {
         // Regardless of whether we requested this transition, the AP has gone
         // down.  Don't try to tether again unless we're requested to do so.
-        // TODO: Remove this altogether, once Wi-Fi reliably gives us an
-        // interface name with every broadcast.
         mWifiTetherRequested = false;
 
-        disableWifiIpServingCommon(TETHERING_WIFI, ifname, apState);
+        mLog.log("Canceling WiFi tethering request - interface=" + ifname + " state=" + apState);
+
+        disableWifiIpServingCommon(TETHERING_WIFI, ifname);
+    }
+
+    private void enableWifiP2pIpServing(String ifname) {
+        if (TextUtils.isEmpty(ifname)) {
+            mLog.e("Cannot enable P2P IP serving with invalid interface");
+            return;
+        }
+
+        // After T, tethering always trust the iface pass by state change intent. This allow
+        // tethering to deprecate tetherable p2p regexs after T.
+        final int type = SdkLevel.isAtLeastT() ? TETHERING_WIFI_P2P : ifaceNameToType(ifname);
+        if (!checkTetherableType(type)) {
+            mLog.e(ifname + " is not a tetherable iface, ignoring");
+            return;
+        }
+        enableIpServing(type, ifname, IpServer.STATE_LOCAL_ONLY);
     }
 
     private void disableWifiP2pIpServingIfNeeded(String ifname) {
         if (TextUtils.isEmpty(ifname)) return;
 
-        disableWifiIpServingCommon(TETHERING_WIFI_P2P, ifname, /* fake */ 0);
+        mLog.log("Canceling P2P tethering request - interface=" + ifname);
+        disableWifiIpServingCommon(TETHERING_WIFI_P2P, ifname);
     }
 
     private void enableWifiIpServing(String ifname, int wifiIpMode) {
+        mLog.log("request WiFi tethering - interface=" + ifname + " state=" + wifiIpMode);
+
         // Map wifiIpMode values to IpServer.Callback serving states, inferring
         // from mWifiTetherRequested as a final "best guess".
         final int ipServingMode;
@@ -1438,13 +1458,18 @@
                 return;
         }
 
+        // After T, tethering always trust the iface pass by state change intent. This allow
+        // tethering to deprecate tetherable wifi regexs after T.
+        final int type = SdkLevel.isAtLeastT() ? TETHERING_WIFI : ifaceNameToType(ifname);
+        if (!checkTetherableType(type)) {
+            mLog.e(ifname + " is not a tetherable iface, ignoring");
+            return;
+        }
+
         if (!TextUtils.isEmpty(ifname)) {
-            ensureIpServerStarted(ifname);
-            changeInterfaceState(ifname, ipServingMode);
+            enableIpServing(type, ifname, ipServingMode);
         } else {
-            mLog.e(String.format(
-                    "Cannot enable IP serving in mode %s on missing interface name",
-                    ipServingMode));
+            mLog.e("Cannot enable IP serving on missing interface name");
         }
     }
 
@@ -2715,23 +2740,28 @@
         mTetherMainSM.sendMessage(which, state, 0, newLp);
     }
 
+    private boolean hasSystemFeature(final String feature) {
+        return mContext.getPackageManager().hasSystemFeature(feature);
+    }
+
+    private boolean checkTetherableType(int type) {
+        if ((type == TETHERING_WIFI || type == TETHERING_WIGIG)
+                && !hasSystemFeature(PackageManager.FEATURE_WIFI)) {
+            return false;
+        }
+
+        if (type == TETHERING_WIFI_P2P && !hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT)) {
+            return false;
+        }
+
+        return type != TETHERING_INVALID;
+    }
+
     private void ensureIpServerStarted(final String iface) {
         // If we don't care about this type of interface, ignore.
         final int interfaceType = ifaceNameToType(iface);
-        if (interfaceType == TETHERING_INVALID) {
-            mLog.log(iface + " is not a tetherable iface, ignoring");
-            return;
-        }
-
-        final PackageManager pm = mContext.getPackageManager();
-        if ((interfaceType == TETHERING_WIFI || interfaceType == TETHERING_WIGIG)
-                && !pm.hasSystemFeature(PackageManager.FEATURE_WIFI)) {
-            mLog.log(iface + " is not tetherable, because WiFi feature is disabled");
-            return;
-        }
-        if (interfaceType == TETHERING_WIFI_P2P
-                && !pm.hasSystemFeature(PackageManager.FEATURE_WIFI_DIRECT)) {
-            mLog.log(iface + " is not tetherable, because WiFi Direct feature is disabled");
+        if (!checkTetherableType(interfaceType)) {
+            mLog.log(iface + " is used for " + interfaceType + " which is not tetherable");
             return;
         }
 
diff --git a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
index 2fd7f48..6ef0e24 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -57,6 +57,7 @@
 import static android.net.wifi.WifiManager.EXTRA_WIFI_AP_STATE;
 import static android.net.wifi.WifiManager.IFACE_IP_MODE_LOCAL_ONLY;
 import static android.net.wifi.WifiManager.IFACE_IP_MODE_TETHERED;
+import static android.net.wifi.WifiManager.WIFI_AP_STATE_DISABLED;
 import static android.net.wifi.WifiManager.WIFI_AP_STATE_ENABLED;
 import static android.system.OsConstants.RT_SCOPE_UNIVERSE;
 import static android.telephony.SubscriptionManager.INVALID_SUBSCRIPTION_ID;
@@ -936,7 +937,7 @@
 
         // Emulate externally-visible WifiManager effects, when hotspot mode
         // is being torn down.
-        sendWifiApStateChanged(WifiManager.WIFI_AP_STATE_DISABLED);
+        sendWifiApStateChanged(WIFI_AP_STATE_DISABLED, TEST_WLAN_IFNAME, IFACE_IP_MODE_LOCAL_ONLY);
         mTethering.interfaceRemoved(TEST_WLAN_IFNAME);
         mLooper.dispatchAll();
 
@@ -1509,7 +1510,7 @@
 
         // Emulate externally-visible WifiManager effects, when tethering mode
         // is being torn down.
-        sendWifiApStateChanged(WifiManager.WIFI_AP_STATE_DISABLED);
+        sendWifiApStateChanged(WIFI_AP_STATE_DISABLED, TEST_WLAN_IFNAME, IFACE_IP_MODE_TETHERED);
         mTethering.interfaceRemoved(TEST_WLAN_IFNAME);
         mLooper.dispatchAll();
 
@@ -1903,7 +1904,13 @@
         mTethering.unregisterTetheringEventCallback(callback);
         mLooper.dispatchAll();
         mTethering.stopTethering(TETHERING_WIFI);
-        sendWifiApStateChanged(WifiManager.WIFI_AP_STATE_DISABLED);
+        sendWifiApStateChanged(WIFI_AP_STATE_DISABLED);
+        if (isAtLeastT()) {
+            // After T, tethering doesn't support WIFI_AP_STATE_DISABLED with null interface name.
+            callback2.assertNoStateChangeCallback();
+            sendWifiApStateChanged(WIFI_AP_STATE_DISABLED, TEST_WLAN_IFNAME,
+                    IFACE_IP_MODE_TETHERED);
+        }
         tetherState = callback2.pollTetherStatesChanged();
         assertArrayEquals(tetherState.availableList, new TetheringInterface[] {wifiIface});
         mLooper.dispatchAll();
diff --git a/service-t/src/com/android/server/ethernet/EthernetConfigStore.java b/service-t/src/com/android/server/ethernet/EthernetConfigStore.java
index 6b623f4..6006539 100644
--- a/service-t/src/com/android/server/ethernet/EthernetConfigStore.java
+++ b/service-t/src/com/android/server/ethernet/EthernetConfigStore.java
@@ -16,23 +16,37 @@
 
 package com.android.server.ethernet;
 
+import static com.android.net.module.util.DeviceConfigUtils.TETHERING_MODULE_NAME;
+
 import android.annotation.Nullable;
+import android.content.ApexEnvironment;
 import android.net.IpConfiguration;
 import android.os.Environment;
 import android.util.ArrayMap;
+import android.util.AtomicFile;
+import android.util.Log;
 
+import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.net.IpConfigStore;
 
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
 
 /**
  * This class provides an API to store and manage Ethernet network configuration.
  */
 public class EthernetConfigStore {
-    private static final String ipConfigFile = Environment.getDataDirectory() +
-            "/misc/ethernet/ipconfig.txt";
+    private static final String TAG = EthernetConfigStore.class.getSimpleName();
+    private static final String CONFIG_FILE = "ipconfig.txt";
+    private static final String FILE_PATH = "/misc/ethernet/";
+    private static final String LEGACY_IP_CONFIG_FILE_PATH = Environment.getDataDirectory()
+            + FILE_PATH;
+    private static final String APEX_IP_CONFIG_FILE_PATH = ApexEnvironment.getApexEnvironment(
+            TETHERING_MODULE_NAME).getDeviceProtectedDataDir() + FILE_PATH;
 
     private IpConfigStore mStore = new IpConfigStore();
-    private ArrayMap<String, IpConfiguration> mIpConfigurations;
+    private final ArrayMap<String, IpConfiguration> mIpConfigurations;
     private IpConfiguration mIpConfigurationForDefaultInterface;
     private final Object mSync = new Object();
 
@@ -40,22 +54,70 @@
         mIpConfigurations = new ArrayMap<>(0);
     }
 
-    public void read() {
-        synchronized (mSync) {
-            ArrayMap<String, IpConfiguration> configs =
-                    IpConfigStore.readIpConfigurations(ipConfigFile);
+    private static boolean doesConfigFileExist(final String filepath) {
+        return new File(filepath).exists();
+    }
 
-            // This configuration may exist in old file versions when there was only a single active
-            // Ethernet interface.
-            if (configs.containsKey("0")) {
-                mIpConfigurationForDefaultInterface = configs.remove("0");
+    private void writeLegacyIpConfigToApexPath(final String newFilePath, final String oldFilePath,
+            final String filename) {
+        final File directory = new File(newFilePath);
+        if (!directory.exists()) {
+            directory.mkdirs();
+        }
+
+        // Write the legacy IP config to the apex file path.
+        FileOutputStream fos = null;
+        final AtomicFile dst = new AtomicFile(new File(newFilePath + filename));
+        final AtomicFile src = new AtomicFile(new File(oldFilePath + filename));
+        try {
+            final byte[] raw = src.readFully();
+            if (raw.length > 0) {
+                fos = dst.startWrite();
+                fos.write(raw);
+                fos.flush();
+                dst.finishWrite(fos);
             }
-
-            mIpConfigurations = configs;
+        } catch (IOException e) {
+            Log.e(TAG, "Fail to sync the legacy IP config to the apex file path.");
+            dst.failWrite(fos);
         }
     }
 
+    public void read() {
+        read(APEX_IP_CONFIG_FILE_PATH, LEGACY_IP_CONFIG_FILE_PATH, CONFIG_FILE);
+    }
+
+    @VisibleForTesting
+    void read(final String newFilePath, final String oldFilePath, final String filename) {
+        synchronized (mSync) {
+            // Attempt to read the IP configuration from apex file path first.
+            if (doesConfigFileExist(newFilePath + filename)) {
+                loadConfigFileLocked(newFilePath + filename);
+                return;
+            }
+
+            // If the config file doesn't exist in the apex file path, attempt to read it from
+            // the legacy file path, if config file exists, write the legacy IP configuration to
+            // apex config file path, this should just happen on the first boot. New or updated
+            // config entries are only written to the apex config file later.
+            if (!doesConfigFileExist(oldFilePath + filename)) return;
+            loadConfigFileLocked(oldFilePath + filename);
+            writeLegacyIpConfigToApexPath(newFilePath, oldFilePath, filename);
+        }
+    }
+
+    private void loadConfigFileLocked(final String filepath) {
+        final ArrayMap<String, IpConfiguration> configs =
+                IpConfigStore.readIpConfigurations(filepath);
+        mIpConfigurations.putAll(configs);
+    }
+
     public void write(String iface, IpConfiguration config) {
+        write(iface, config, APEX_IP_CONFIG_FILE_PATH + CONFIG_FILE);
+    }
+
+    @VisibleForTesting
+    void write(String iface, IpConfiguration config, String filepath) {
         boolean modified;
 
         synchronized (mSync) {
@@ -67,7 +129,7 @@
             }
 
             if (modified) {
-                mStore.writeIpConfigurations(ipConfigFile, mIpConfigurations);
+                mStore.writeIpConfigurations(filepath, mIpConfigurations);
             }
         }
     }
@@ -80,9 +142,6 @@
 
     @Nullable
     public IpConfiguration getIpConfigurationForDefaultInterface() {
-        synchronized (mSync) {
-            return mIpConfigurationForDefaultInterface == null
-                    ? null : new IpConfiguration(mIpConfigurationForDefaultInterface);
-        }
+        return null;
     }
 }
diff --git a/tests/unit/java/com/android/server/ethernet/EthernetConfigStoreTest.java b/tests/unit/java/com/android/server/ethernet/EthernetConfigStoreTest.java
new file mode 100644
index 0000000..a9f80ea
--- /dev/null
+++ b/tests/unit/java/com/android/server/ethernet/EthernetConfigStoreTest.java
@@ -0,0 +1,143 @@
+/*
+ * Copyright (C) 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.ethernet;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import android.content.Context;
+import android.net.InetAddresses;
+import android.net.IpConfiguration;
+import android.net.IpConfiguration.IpAssignment;
+import android.net.IpConfiguration.ProxySettings;
+import android.net.LinkAddress;
+import android.net.ProxyInfo;
+import android.net.StaticIpConfiguration;
+import android.util.ArrayMap;
+
+import androidx.test.InstrumentationRegistry;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.io.File;
+import java.net.InetAddress;
+import java.util.ArrayList;
+import java.util.List;
+
+@RunWith(AndroidJUnit4.class)
+public class EthernetConfigStoreTest {
+    private static final LinkAddress LINKADDR = new LinkAddress("192.168.1.100/25");
+    private static final InetAddress GATEWAY = InetAddresses.parseNumericAddress("192.168.1.1");
+    private static final InetAddress DNS1 = InetAddresses.parseNumericAddress("8.8.8.8");
+    private static final InetAddress DNS2 = InetAddresses.parseNumericAddress("8.8.4.4");
+    private static final StaticIpConfiguration STATIC_IP_CONFIG =
+            new StaticIpConfiguration.Builder()
+                    .setIpAddress(LINKADDR)
+                    .setGateway(GATEWAY)
+                    .setDnsServers(new ArrayList<InetAddress>(
+                            List.of(DNS1, DNS2)))
+                    .build();
+    private static final ProxyInfo PROXY_INFO = ProxyInfo.buildDirectProxy("test", 8888);
+    private static final IpConfiguration APEX_IP_CONFIG =
+            new IpConfiguration(IpAssignment.DHCP, ProxySettings.NONE, null, null);
+    private static final IpConfiguration LEGACY_IP_CONFIG =
+            new IpConfiguration(IpAssignment.STATIC, ProxySettings.STATIC, STATIC_IP_CONFIG,
+                    PROXY_INFO);
+
+    private EthernetConfigStore mEthernetConfigStore;
+    private File mApexTestDir;
+    private File mLegacyTestDir;
+    private File mApexConfigFile;
+    private File mLegacyConfigFile;
+
+    private void createTestDir() {
+        final Context context = InstrumentationRegistry.getContext();
+        final File baseDir = context.getFilesDir();
+        mApexTestDir = new File(baseDir.getPath() + "/apex");
+        mApexTestDir.mkdirs();
+
+        mLegacyTestDir = new File(baseDir.getPath() + "/legacy");
+        mLegacyTestDir.mkdirs();
+    }
+
+    @Before
+    public void setUp() {
+        createTestDir();
+        mEthernetConfigStore = new EthernetConfigStore();
+    }
+
+    @After
+    public void tearDown() {
+        mApexTestDir.delete();
+        mLegacyTestDir.delete();
+    }
+
+    private void assertConfigFileExist(final String filepath) {
+        assertTrue(new File(filepath).exists());
+    }
+
+    /** Wait for the delayed write operation completes. */
+    private void waitForMs(long ms) {
+        try {
+            Thread.sleep(ms);
+        } catch (final InterruptedException e) {
+            fail("Thread was interrupted");
+        }
+    }
+
+    @Test
+    public void testWriteIpConfigToApexFilePathAndRead() throws Exception {
+        // Write the config file to the apex file path, pretend the config file exits and
+        // check if IP config should be read from apex file path.
+        mApexConfigFile = new File(mApexTestDir.getPath(), "test.txt");
+        mEthernetConfigStore.write("eth0", APEX_IP_CONFIG, mApexConfigFile.getPath());
+        waitForMs(50);
+
+        mEthernetConfigStore.read(mApexTestDir.getPath(), mLegacyTestDir.getPath(), "/test.txt");
+        final ArrayMap<String, IpConfiguration> ipConfigurations =
+                mEthernetConfigStore.getIpConfigurations();
+        assertEquals(APEX_IP_CONFIG, ipConfigurations.get("eth0"));
+
+        mApexConfigFile.delete();
+    }
+
+    @Test
+    public void testWriteIpConfigToLegacyFilePathAndRead() throws Exception {
+        // Write the config file to the legacy file path, pretend the config file exits and
+        // check if IP config should be read from legacy file path.
+        mLegacyConfigFile = new File(mLegacyTestDir, "test.txt");
+        mEthernetConfigStore.write("0", LEGACY_IP_CONFIG, mLegacyConfigFile.getPath());
+        waitForMs(50);
+
+        mEthernetConfigStore.read(mApexTestDir.getPath(), mLegacyTestDir.getPath(), "/test.txt");
+        final ArrayMap<String, IpConfiguration> ipConfigurations =
+                mEthernetConfigStore.getIpConfigurations();
+        assertEquals(LEGACY_IP_CONFIG, ipConfigurations.get("0"));
+
+        // Check the same config file in apex file path is created.
+        assertConfigFileExist(mApexTestDir.getPath() + "/test.txt");
+
+        final File apexConfigFile = new File(mApexTestDir.getPath() + "/test.txt");
+        apexConfigFile.delete();
+        mLegacyConfigFile.delete();
+    }
+}