diff --git a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
index e81cbf0..21f36e8 100644
--- a/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
+++ b/Tethering/common/TetheringLib/src/android/net/TetheringManager.java
@@ -28,6 +28,7 @@
 import android.content.Context;
 import android.net.wifi.SoftApConfiguration;
 import android.net.wifi.WifiManager;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.ConditionVariable;
 import android.os.IBinder;
@@ -657,6 +658,13 @@
         }
     }
 
+    private void unsupportedAfterV() {
+        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.VANILLA_ICE_CREAM) {
+            throw new UnsupportedOperationException("Not supported after SDK version "
+                    + Build.VERSION_CODES.VANILLA_ICE_CREAM);
+        }
+    }
+
     /**
      * Attempt to tether the named interface.  This will setup a dhcp server
      * on the interface, forward and NAT IP v4 packets and forward DNS requests
@@ -666,8 +674,10 @@
      * access will of course fail until an upstream network interface becomes
      * active.
      *
-     * @deprecated The only usages is PanService. It uses this for legacy reasons
-     * and will migrate away as soon as possible.
+     * @deprecated Legacy tethering API. Callers should instead use
+     *             {@link #startTethering(int, Executor, StartTetheringCallback)}.
+     *             On SDK versions after {@link Build.VERSION_CODES.VANILLA_ICE_CREAM}, this will
+     *             throw an UnsupportedOperationException.
      *
      * @param iface the interface name to tether.
      * @return error a {@code TETHER_ERROR} value indicating success or failure type
@@ -677,6 +687,8 @@
     @Deprecated
     @SystemApi(client = MODULE_LIBRARIES)
     public int tether(@NonNull final String iface) {
+        unsupportedAfterV();
+
         final String callerPkg = mContext.getOpPackageName();
         Log.i(TAG, "tether caller:" + callerPkg);
         final RequestDispatcher dispatcher = new RequestDispatcher();
@@ -700,14 +712,18 @@
     /**
      * Stop tethering the named interface.
      *
-     * @deprecated The only usages is PanService. It uses this for legacy reasons
-     * and will migrate away as soon as possible.
+     * @deprecated Legacy tethering API. Callers should instead use
+     *             {@link #stopTethering(int)}.
+     *             On SDK versions after {@link Build.VERSION_CODES.VANILLA_ICE_CREAM}, this will
+     *             throw an UnsupportedOperationException.
      *
      * {@hide}
      */
     @Deprecated
     @SystemApi(client = MODULE_LIBRARIES)
     public int untether(@NonNull final String iface) {
+        unsupportedAfterV();
+
         final String callerPkg = mContext.getOpPackageName();
         Log.i(TAG, "untether caller:" + callerPkg);
 
diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 4f07f58..40b1ec0 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -108,6 +108,7 @@
 import android.net.wifi.p2p.WifiP2pInfo;
 import android.net.wifi.p2p.WifiP2pManager;
 import android.os.Binder;
+import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Looper;
@@ -600,13 +601,40 @@
     // This method needs to exist because TETHERING_BLUETOOTH before Android T and TETHERING_WIGIG
     // can't use enableIpServing.
     private void processInterfaceStateChange(final String iface, boolean enabled) {
+        final int type = ifaceNameToType(iface);
         // Do not listen to USB interface state changes or USB interface add/removes. USB tethering
         // is driven only by USB_ACTION broadcasts.
-        final int type = ifaceNameToType(iface);
         if (type == TETHERING_USB || type == TETHERING_NCM) return;
 
+        // On T+, BLUETOOTH uses enableIpServing.
         if (type == TETHERING_BLUETOOTH && SdkLevel.isAtLeastT()) return;
 
+        // Cannot happen: on S+, tetherableWigigRegexps is always empty.
+        if (type == TETHERING_WIGIG && SdkLevel.isAtLeastS()) return;
+
+        // After V, disallow this legacy codepath from starting tethering of any type:
+        // everything must call ensureIpServerStarted directly.
+        //
+        // Don't touch the teardown path for now. It's more complicated because:
+        // - ensureIpServerStarted and ensureIpServerStopped act on different
+        //   tethering types.
+        // - Depending on the type, ensureIpServerStopped is either called twice (once
+        //   on interface down and once on interface removed) or just once (on
+        //   interface removed).
+        //
+        // Note that this only affects WIFI and WIFI_P2P. The other types are either
+        // ignored above, or ignored by ensureIpServerStarted. Note that even for WIFI
+        // and WIFI_P2P, this code should not ever run in normal use, because the
+        // hotspot and p2p code do not call tether(). It's possible that this could
+        // happen in the field due to unforeseen OEM modifications. If it does happen,
+        // a terrible error is logged in tether().
+        // TODO: fix the teardown path to stop depending on interface state notifications.
+        // These are not necessary since most/all link layers have their own teardown
+        // notifications, and can race with those notifications.
+        if (enabled && Build.VERSION.SDK_INT > Build.VERSION_CODES.VANILLA_ICE_CREAM) {
+            return;
+        }
+
         if (enabled) {
             ensureIpServerStarted(iface);
         } else {
@@ -999,7 +1027,27 @@
         return TETHER_ERROR_NO_ERROR;
     }
 
+    /**
+     * Legacy tether API that starts tethering with CONNECTIVITY_SCOPE_GLOBAL on the given iface.
+     *
+     * This API relies on the IpServer having been started for the interface by
+     * processInterfaceStateChanged beforehand, which is only possible for
+     *     - WIGIG Pre-S
+     *     - BLUETOOTH Pre-T
+     *     - WIFI
+     *     - WIFI_P2P.
+     * Note that WIFI and WIFI_P2P already start tethering on their respective ifaces via
+     * WIFI_(AP/P2P_STATE_CHANGED broadcasts, which makes this API redundant for those types unless
+     * those broadcasts are disabled by OEM.
+     */
     void tether(String iface, int requestedState, final IIntResultListener listener) {
+        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.VANILLA_ICE_CREAM) {
+            // After V, the TetheringManager and ConnectivityManager tether and untether methods
+            // throw UnsupportedOperationException, so this cannot happen in normal use. Ensure
+            // that this code cannot run even if callers use raw binder calls or other
+            // unsupported methods.
+            return;
+        }
         mHandler.post(() -> {
             switch (ifaceNameToType(iface)) {
                 case TETHERING_WIFI:
@@ -1051,6 +1099,13 @@
     }
 
     void untether(String iface, final IIntResultListener listener) {
+        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.VANILLA_ICE_CREAM) {
+            // After V, the TetheringManager and ConnectivityManager tether and untether methods
+            // throw UnsupportedOperationException, so this cannot happen in normal use. Ensure
+            // that this code cannot run even if callers use raw binder calls or other
+            // unsupported methods.
+            return;
+        }
         mHandler.post(() -> {
             try {
                 listener.onResult(untether(iface));
diff --git a/framework/src/android/net/ConnectivityManager.java b/framework/src/android/net/ConnectivityManager.java
index 9016d13..5d99b74 100644
--- a/framework/src/android/net/ConnectivityManager.java
+++ b/framework/src/android/net/ConnectivityManager.java
@@ -3065,7 +3065,8 @@
      * <p>WARNING: New clients should not use this function. The only usages should be in PanService
      * and WifiStateMachine which need direct access. All other clients should use
      * {@link #startTethering} and {@link #stopTethering} which encapsulate proper provisioning
-     * logic.</p>
+     * logic. On SDK versions after {@link Build.VERSION_CODES.VANILLA_ICE_CREAM}, this will throw
+     * an UnsupportedOperationException.</p>
      *
      * @param iface the interface name to tether.
      * @return error a {@code TETHER_ERROR} value indicating success or failure type
@@ -3090,7 +3091,8 @@
      * <p>WARNING: New clients should not use this function. The only usages should be in PanService
      * and WifiStateMachine which need direct access. All other clients should use
      * {@link #startTethering} and {@link #stopTethering} which encapsulate proper provisioning
-     * logic.</p>
+     * logic. On SDK versions after {@link Build.VERSION_CODES.VANILLA_ICE_CREAM}, this will throw
+     * an UnsupportedOperationException.</p>
      *
      * @param iface the interface name to untether.
      * @return error a {@code TETHER_ERROR} value indicating success or failure type
diff --git a/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java b/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
index 5e94c06..2420026 100644
--- a/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
+++ b/tests/cts/tethering/src/android/tethering/cts/TetheringManagerTest.java
@@ -45,6 +45,7 @@
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertThrows;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 import static org.junit.Assume.assumeFalse;
@@ -387,18 +388,21 @@
 
             mCtsTetheringUtils.stopWifiTethering(tetherEventCallback);
 
-            try {
-                final int ret = runAsShell(TETHER_PRIVILEGED, () -> mTM.tether(wifiTetheringIface));
-                // There is no guarantee that the wifi interface will be available after disabling
-                // the hotspot, so don't fail the test if the call to tether() fails.
-                if (ret == TETHER_ERROR_NO_ERROR) {
-                    // If calling #tether successful, there is a callback to tell the result of
-                    // tethering setup.
-                    tetherEventCallback.expectErrorOrTethered(
-                            new TetheringInterface(TETHERING_WIFI, wifiTetheringIface));
+            if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.VANILLA_ICE_CREAM) {
+                try {
+                    final int ret = runAsShell(TETHER_PRIVILEGED,
+                            () -> mTM.tether(wifiTetheringIface));
+                    // There is no guarantee that the wifi interface will be available after
+                    // disabling the hotspot, so don't fail the test if the call to tether() fails.
+                    if (ret == TETHER_ERROR_NO_ERROR) {
+                        // If calling #tether successful, there is a callback to tell the result of
+                        // tethering setup.
+                        tetherEventCallback.expectErrorOrTethered(
+                                new TetheringInterface(TETHERING_WIFI, wifiTetheringIface));
+                    }
+                } finally {
+                    runAsShell(TETHER_PRIVILEGED, () -> mTM.untether(wifiTetheringIface));
                 }
-            } finally {
-                runAsShell(TETHER_PRIVILEGED, () -> mTM.untether(wifiTetheringIface));
             }
         } finally {
             mCtsTetheringUtils.unregisterTetheringEventCallback(tetherEventCallback);
@@ -623,4 +627,11 @@
             }
         }
     }
+
+    @Test
+    public void testLegacyTetherApisThrowUnsupportedOperationExceptionAfterV() {
+        assumeTrue(Build.VERSION.SDK_INT > Build.VERSION_CODES.VANILLA_ICE_CREAM);
+        assertThrows(UnsupportedOperationException.class, () -> mTM.tether("iface"));
+        assertThrows(UnsupportedOperationException.class, () -> mTM.untether("iface"));
+    }
 }
diff --git a/tests/unit/java/android/net/ConnectivityManagerTest.java b/tests/unit/java/android/net/ConnectivityManagerTest.java
index 9a77c89..b415382 100644
--- a/tests/unit/java/android/net/ConnectivityManagerTest.java
+++ b/tests/unit/java/android/net/ConnectivityManagerTest.java
@@ -44,6 +44,7 @@
 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.ArgumentMatchers.anyBoolean;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.ArgumentMatchers.nullable;
@@ -65,6 +66,7 @@
 import android.content.Context;
 import android.content.pm.ApplicationInfo;
 import android.net.ConnectivityManager.NetworkCallback;
+import android.os.Build;
 import android.os.Build.VERSION_CODES;
 import android.os.Bundle;
 import android.os.Handler;
@@ -669,4 +671,12 @@
                 // No callbacks overridden -> do not use the optimization
                 eq(~0));
     }
+
+    @Test
+    public void testLegacyTetherApisThrowUnsupportedOperationExceptionAfterV() {
+        assumeTrue(Build.VERSION.SDK_INT > Build.VERSION_CODES.VANILLA_ICE_CREAM);
+        final ConnectivityManager manager = new ConnectivityManager(mCtx, mService);
+        assertThrows(UnsupportedOperationException.class, () -> manager.tether("iface"));
+        assertThrows(UnsupportedOperationException.class, () -> manager.untether("iface"));
+    }
 }