diff --git a/services/core/java/com/android/server/ConnectivityService.java b/services/core/java/com/android/server/ConnectivityService.java
index b5fcde4..113d92c 100644
--- a/services/core/java/com/android/server/ConnectivityService.java
+++ b/services/core/java/com/android/server/ConnectivityService.java
@@ -2877,7 +2877,7 @@
             e.rethrowFromSystemServer();
         }
         mNetworkAgentInfos.remove(nai.messenger);
-        nai.maybeStopClat();
+        nai.updateClat();
         synchronized (mNetworkForNetId) {
             // Remove the NetworkAgent, but don't mark the netId as
             // available until we've told netd to delete it below.
@@ -5185,11 +5185,10 @@
             LinkProperties oldLp) {
         int netId = networkAgent.network.netId;
 
-        // The NetworkAgentInfo does not know whether clatd is running on its network or not. Before
-        // we do anything else, make sure its LinkProperties are accurate.
-        if (networkAgent.clatd != null) {
-            networkAgent.clatd.fixupLinkProperties(oldLp, newLp);
-        }
+        // The NetworkAgentInfo does not know whether clatd is running on its network or not, or
+        // whether there is a NAT64 prefix. Before we do anything else, make sure its LinkProperties
+        // are accurate.
+        networkAgent.clatd.fixupLinkProperties(oldLp, newLp);
 
         updateInterfaces(newLp, oldLp, netId, networkAgent.networkCapabilities);
         updateMtu(newLp, oldLp);
@@ -5220,7 +5219,7 @@
                 networkAgent.linkProperties = newLp;
             }
             // Start or stop clat accordingly to network state.
-            networkAgent.updateClat(mNMS);
+            networkAgent.updateClat();
             notifyIfacesChangedForNetworkStats();
             if (networkAgent.everConnected) {
                 try {
diff --git a/services/core/java/com/android/server/connectivity/Nat464Xlat.java b/services/core/java/com/android/server/connectivity/Nat464Xlat.java
index 9d9b1cf..c834eaa 100644
--- a/services/core/java/com/android/server/connectivity/Nat464Xlat.java
+++ b/services/core/java/com/android/server/connectivity/Nat464Xlat.java
@@ -70,8 +70,6 @@
         IDLE,       // start() not called. Base iface and stacked iface names are null.
         STARTING,   // start() called. Base iface and stacked iface names are known.
         RUNNING,    // start() called, and the stacked iface is known to be up.
-        STOPPING;   // stop() called, this Nat464Xlat is still registered as a network observer for
-                    // the stacked interface.
     }
 
     private String mBaseIface;
@@ -124,27 +122,19 @@
     }
 
     /**
-     * @return true if clatd has been stopped.
-     */
-    public boolean isStopping() {
-        return mState == State.STOPPING;
-    }
-
-    /**
      * Start clatd, register this Nat464Xlat as a network observer for the stacked interface,
      * and set internal state.
      */
     private void enterStartingState(String baseIface) {
         try {
             mNMService.registerObserver(this);
-        } catch(RemoteException e) {
-            Slog.e(TAG,
-                    "startClat: Can't register interface observer for clat on " + mNetwork.name());
+        } catch (RemoteException e) {
+            Slog.e(TAG, "Can't register interface observer for clat on " + mNetwork.name());
             return;
         }
         try {
             mNetd.clatdStart(baseIface);
-        } catch(RemoteException|IllegalStateException e) {
+        } catch (RemoteException | IllegalStateException e) {
             Slog.e(TAG, "Error starting clatd on " + baseIface, e);
         }
         mIface = CLAT_PREFIX + baseIface;
@@ -161,28 +151,14 @@
     }
 
     /**
-     * Stop clatd, and turn ND offload on if it had been turned off.
-     */
-    private void enterStoppingState() {
-        try {
-            mNetd.clatdStop(mBaseIface);
-        } catch(RemoteException|IllegalStateException e) {
-            Slog.e(TAG, "Error stopping clatd on " + mBaseIface, e);
-        }
-
-        mState = State.STOPPING;
-    }
-
-    /**
      * Unregister as a base observer for the stacked interface, and clear internal state.
      */
     private void enterIdleState() {
         try {
             mNMService.unregisterObserver(this);
-        } catch(RemoteException|IllegalStateException e) {
+        } catch (RemoteException | IllegalStateException e) {
             Slog.e(TAG, "Error unregistering clatd observer on " + mBaseIface, e);
         }
-
         mIface = null;
         mBaseIface = null;
         mState = State.IDLE;
@@ -217,14 +193,30 @@
      */
     public void stop() {
         if (!isStarted()) {
+            Slog.e(TAG, "stopClat: already stopped");
             return;
         }
-        Slog.i(TAG, "Stopping clatd on " + mBaseIface);
 
-        boolean wasStarting = isStarting();
-        enterStoppingState();
-        if (wasStarting) {
-            enterIdleState();
+        Slog.i(TAG, "Stopping clatd on " + mBaseIface);
+        try {
+            mNetd.clatdStop(mBaseIface);
+        } catch (RemoteException | IllegalStateException e) {
+            Slog.e(TAG, "Error stopping clatd on " + mBaseIface, e);
+        }
+
+        String iface = mIface;
+        boolean wasRunning = isRunning();
+
+        // Enter IDLE state before updating LinkProperties. handleUpdateLinkProperties ends up
+        // calling fixupLinkProperties, and if at that time the state is still RUNNING,
+        // fixupLinkProperties would wrongly inform ConnectivityService that there is still a
+        // stacked interface.
+        enterIdleState();
+
+        if (wasRunning) {
+            LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
+            lp.removeStackedLink(iface);
+            mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp);
         }
     }
 
@@ -272,7 +264,7 @@
         try {
             InterfaceConfiguration config = mNMService.getInterfaceConfig(iface);
             return config.getLinkAddress();
-        } catch(RemoteException|IllegalStateException e) {
+        } catch (RemoteException | IllegalStateException e) {
             Slog.e(TAG, "Error getting link properties: " + e);
             return null;
         }
@@ -307,20 +299,16 @@
         if (!Objects.equals(mIface, iface)) {
             return;
         }
-        if (!isRunning() && !isStopping()) {
+        if (!isRunning()) {
             return;
         }
 
         Slog.i(TAG, "interface " + iface + " removed");
-        if (!isStopping()) {
-            // Ensure clatd is stopped if stop() has not been called: this likely means that clatd
-            // has crashed.
-            enterStoppingState();
-        }
-        enterIdleState();
-        LinkProperties lp = new LinkProperties(mNetwork.linkProperties);
-        lp.removeStackedLink(iface);
-        mNetwork.connService().handleUpdateLinkProperties(mNetwork, lp);
+        // If we're running, and the interface was removed, then we didn't call stop(), and it's
+        // likely that clatd crashed. Ensure we call stop() so we can start clatd again. Calling
+        // stop() will also update LinkProperties, and if clatd crashed, the LinkProperties update
+        // will cause ConnectivityService to call start() again.
+        stop();
     }
 
     @Override
diff --git a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
index d0cff25..96f7283 100644
--- a/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
+++ b/services/core/java/com/android/server/connectivity/NetworkAgentInfo.java
@@ -236,7 +236,7 @@
     public final AsyncChannel asyncChannel;
 
     // Used by ConnectivityService to keep track of 464xlat.
-    public Nat464Xlat clatd;
+    public final Nat464Xlat clatd;
 
     // Set after asynchronous creation of the NetworkMonitor.
     private volatile INetworkMonitor mNetworkMonitor;
@@ -244,8 +244,6 @@
     private static final String TAG = ConnectivityService.class.getSimpleName();
     private static final boolean VDBG = false;
     private final ConnectivityService mConnService;
-    private final INetd mNetd;
-    private final INetworkManagementService mNMS;
     private final Context mContext;
     private final Handler mHandler;
 
@@ -260,9 +258,8 @@
         linkProperties = lp;
         networkCapabilities = nc;
         currentScore = score;
+        clatd = new Nat464Xlat(this, netd, nms);
         mConnService = connService;
-        mNetd = netd;
-        mNMS = nms;
         mContext = context;
         mHandler = handler;
         networkMisc = misc;
@@ -595,32 +592,15 @@
         for (LingerTimer timer : mLingerTimers) { pw.println(timer); }
     }
 
-    public void updateClat(INetworkManagementService netd) {
-        if (Nat464Xlat.requiresClat(this)) {
-            maybeStartClat();
-        } else {
-            maybeStopClat();
+    /** Starts or stops clatd as required. */
+    public void updateClat() {
+        if (!clatd.isStarted() && Nat464Xlat.requiresClat(this)) {
+            clatd.start();
+        } else if (clatd.isStarted() && !Nat464Xlat.requiresClat(this)) {
+            clatd.stop();
         }
     }
 
-    /** Ensure clat has started for this network. */
-    public void maybeStartClat() {
-        if (clatd != null && clatd.isStarted()) {
-            return;
-        }
-        clatd = new Nat464Xlat(this, mNetd, mNMS);
-        clatd.start();
-    }
-
-    /** Ensure clat has stopped for this network. */
-    public void maybeStopClat() {
-        if (clatd == null) {
-            return;
-        }
-        clatd.stop();
-        clatd = null;
-    }
-
     public String toString() {
         return "NetworkAgentInfo{ ni{" + networkInfo + "}  "
                 + "network{" + network + "}  nethandle{" + network.getNetworkHandle() + "}  "
diff --git a/tests/net/java/com/android/server/connectivity/Nat464XlatTest.java b/tests/net/java/com/android/server/connectivity/Nat464XlatTest.java
index 07b1d05..b9450b3 100644
--- a/tests/net/java/com/android/server/connectivity/Nat464XlatTest.java
+++ b/tests/net/java/com/android/server/connectivity/Nat464XlatTest.java
@@ -19,6 +19,7 @@
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.eq;
+import static org.mockito.Mockito.inOrder;
 import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
@@ -43,6 +44,7 @@
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.mockito.ArgumentCaptor;
+import org.mockito.InOrder;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
@@ -145,20 +147,106 @@
         nat.stop();
 
         verify(mNetd).clatdStop(eq(BASE_IFACE));
-
-        // Stacked interface removed notification arrives.
-        nat.interfaceRemoved(STACKED_IFACE);
-        mLooper.dispatchNext();
-
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mConnectivity, times(2)).handleUpdateLinkProperties(eq(mNai), c.capture());
+        verify(mNms).unregisterObserver(eq(nat));
         assertTrue(c.getValue().getStackedLinks().isEmpty());
         assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
         assertIdle(nat);
 
+        // Stacked interface removed notification arrives and is ignored.
+        nat.interfaceRemoved(STACKED_IFACE);
+        mLooper.dispatchNext();
+
         verifyNoMoreInteractions(mNetd, mNms, mConnectivity);
     }
 
+    private void checkStartStopStart(boolean interfaceRemovedFirst) throws Exception {
+        Nat464Xlat nat = makeNat464Xlat();
+        ArgumentCaptor<LinkProperties> c = ArgumentCaptor.forClass(LinkProperties.class);
+        InOrder inOrder = inOrder(mNetd, mConnectivity);
+
+        // ConnectivityService starts clat.
+        nat.start();
+
+        inOrder.verify(mNetd).clatdStart(eq(BASE_IFACE));
+
+        // Stacked interface up notification arrives.
+        nat.interfaceLinkStateChanged(STACKED_IFACE, true);
+        mLooper.dispatchNext();
+
+        inOrder.verify(mConnectivity).handleUpdateLinkProperties(eq(mNai), c.capture());
+        assertFalse(c.getValue().getStackedLinks().isEmpty());
+        assertTrue(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
+        assertRunning(nat);
+
+        // ConnectivityService stops clat (Network disconnects, IPv4 addr appears, ...).
+        nat.stop();
+
+        inOrder.verify(mNetd).clatdStop(eq(BASE_IFACE));
+
+        inOrder.verify(mConnectivity, times(1)).handleUpdateLinkProperties(eq(mNai), c.capture());
+        assertTrue(c.getValue().getStackedLinks().isEmpty());
+        assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
+        assertIdle(nat);
+
+        if (interfaceRemovedFirst) {
+            // Stacked interface removed notification arrives and is ignored.
+            nat.interfaceRemoved(STACKED_IFACE);
+            mLooper.dispatchNext();
+            nat.interfaceLinkStateChanged(STACKED_IFACE, false);
+            mLooper.dispatchNext();
+        }
+
+        assertTrue(c.getValue().getStackedLinks().isEmpty());
+        assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
+        assertIdle(nat);
+        inOrder.verifyNoMoreInteractions();
+
+        // ConnectivityService starts clatd again.
+        nat.start();
+
+        inOrder.verify(mNetd).clatdStart(eq(BASE_IFACE));
+
+        if (!interfaceRemovedFirst) {
+            // Stacked interface removed notification arrives and is ignored.
+            nat.interfaceRemoved(STACKED_IFACE);
+            mLooper.dispatchNext();
+            nat.interfaceLinkStateChanged(STACKED_IFACE, false);
+            mLooper.dispatchNext();
+        }
+
+        // Stacked interface up notification arrives.
+        nat.interfaceLinkStateChanged(STACKED_IFACE, true);
+        mLooper.dispatchNext();
+
+        inOrder.verify(mConnectivity).handleUpdateLinkProperties(eq(mNai), c.capture());
+        assertFalse(c.getValue().getStackedLinks().isEmpty());
+        assertTrue(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
+        assertRunning(nat);
+
+        // ConnectivityService stops clat again.
+        nat.stop();
+
+        inOrder.verify(mNetd).clatdStop(eq(BASE_IFACE));
+
+        inOrder.verify(mConnectivity, times(1)).handleUpdateLinkProperties(eq(mNai), c.capture());
+        assertTrue(c.getValue().getStackedLinks().isEmpty());
+        assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
+        assertIdle(nat);
+
+        inOrder.verifyNoMoreInteractions();
+    }
+
+    @Test
+    public void testStartStopStart() throws Exception {
+        checkStartStopStart(true);
+    }
+
+    @Test
+    public void testStartStopStartBeforeInterfaceRemoved() throws Exception {
+        checkStartStopStart(false);
+    }
+
     @Test
     public void testClatdCrashWhileRunning() throws Exception {
         Nat464Xlat nat = makeNat464Xlat();
@@ -184,9 +272,9 @@
         nat.interfaceRemoved(STACKED_IFACE);
         mLooper.dispatchNext();
 
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mNetd).clatdStop(eq(BASE_IFACE));
         verify(mConnectivity, times(2)).handleUpdateLinkProperties(eq(mNai), c.capture());
+        verify(mNms).unregisterObserver(eq(nat));
         assertTrue(c.getValue().getStackedLinks().isEmpty());
         assertFalse(c.getValue().getAllInterfaceNames().contains(STACKED_IFACE));
         assertIdle(nat);
@@ -210,8 +298,8 @@
         // ConnectivityService immediately stops clat (Network disconnects, IPv4 addr appears, ...)
         nat.stop();
 
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mNetd).clatdStop(eq(BASE_IFACE));
+        verify(mNms).unregisterObserver(eq(nat));
         assertIdle(nat);
 
         // In-flight interface up notification arrives: no-op
@@ -241,8 +329,8 @@
         // ConnectivityService immediately stops clat (Network disconnects, IPv4 addr appears, ...)
         nat.stop();
 
-        verify(mNms).unregisterObserver(eq(nat));
         verify(mNetd).clatdStop(eq(BASE_IFACE));
+        verify(mNms).unregisterObserver(eq(nat));
         assertIdle(nat);
 
         verifyNoMoreInteractions(mNetd, mNms, mConnectivity);