diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 5e14be5..e6bc501 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -319,6 +319,7 @@
 import java.io.InterruptedIOException;
 import java.io.PrintWriter;
 import java.io.Writer;
+import java.lang.IllegalArgumentException;
 import java.net.Inet4Address;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
@@ -4011,7 +4012,7 @@
                     // the destroyed flag is only just above the "current satisfier wins"
                     // tie-breaker. But technically anything that affects scoring should rematch.
                     rematchAllNetworksAndRequests();
-                    mHandler.postDelayed(() -> disconnectAndDestroyNetwork(nai), timeoutMs);
+                    mHandler.postDelayed(() -> nai.disconnect(), timeoutMs);
                     break;
                 }
             }
@@ -4548,9 +4549,11 @@
 
     @VisibleForTesting
     protected static boolean shouldCreateNetworksImmediately() {
-        // Before U, physical networks are only created when the agent advances to CONNECTED.
-        // In U and above, all networks are immediately created when the agent is registered.
-        return SdkLevel.isAtLeastU();
+        // The feature of creating the networks immediately was slated for U, but race conditions
+        // detected late required this was flagged off.
+        // TODO : enable this in a Mainline update or in V, and re-enable the test for this
+        // in NetworkAgentTest.
+        return false;
     }
 
     private static boolean shouldCreateNativeNetwork(@NonNull NetworkAgentInfo nai,
@@ -4610,9 +4613,6 @@
         if (DBG) {
             log(nai.toShortString() + " disconnected, was satisfying " + nai.numNetworkRequests());
         }
-
-        nai.disconnect();
-
         // Clear all notifications of this network.
         mNotifier.clearNotification(nai.network.getNetId());
         // A network agent has disconnected.
@@ -5897,7 +5897,7 @@
                     final NetworkAgentInfo nai = getNetworkAgentInfoForNetwork((Network) msg.obj);
                     if (nai == null) break;
                     nai.onPreventAutomaticReconnect();
-                    disconnectAndDestroyNetwork(nai);
+                    nai.disconnect();
                     break;
                 case EVENT_SET_VPN_NETWORK_PREFERENCE:
                     handleSetVpnNetworkPreference((VpnNetworkPreferenceInfo) msg.obj);
@@ -9044,7 +9044,7 @@
                 break;
             }
         }
-        disconnectAndDestroyNetwork(nai);
+        nai.disconnect();
     }
 
     private void handleLingerComplete(NetworkAgentInfo oldNetwork) {
@@ -9586,10 +9586,7 @@
         updateLegacyTypeTrackerAndVpnLockdownForRematch(changes, nais);
 
         // Tear down all unneeded networks.
-        // Iterate in reverse order because teardownUnneededNetwork removes the nai from
-        // mNetworkAgentInfos.
-        for (int i = mNetworkAgentInfos.size() - 1; i >= 0; i--) {
-            final NetworkAgentInfo nai = mNetworkAgentInfos.valueAt(i);
+        for (NetworkAgentInfo nai : mNetworkAgentInfos) {
             if (unneeded(nai, UnneededFor.TEARDOWN)) {
                 if (nai.getInactivityExpiry() > 0) {
                     // This network has active linger timers and no requests, but is not
@@ -9972,6 +9969,7 @@
             // This has to happen after matching the requests, because callbacks are just requests.
             notifyNetworkCallbacks(networkAgent, ConnectivityManager.CALLBACK_PRECHECK);
         } else if (state == NetworkInfo.State.DISCONNECTED) {
+            networkAgent.disconnect();
             if (networkAgent.isVPN()) {
                 updateVpnUids(networkAgent, networkAgent.networkCapabilities, null);
             }
diff --git a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
index 9f8a05d..5879065 100644
--- a/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
+++ b/tests/cts/net/src/android/net/cts/NetworkAgentTest.kt
@@ -130,6 +130,7 @@
 import kotlin.test.assertTrue
 import kotlin.test.fail
 import org.junit.After
+import org.junit.Assume.assumeFalse
 import org.junit.Before
 import org.junit.Test
 import org.junit.runner.RunWith
@@ -164,6 +165,12 @@
     it.obj = obj
 }
 
+// On T and below, the native network is only created when the agent connects.
+// Starting in U, the native network was to be created as soon as the agent is registered,
+// but this has been flagged off for now pending resolution of race conditions.
+// TODO : enable this in a Mainline update or in V.
+private const val SHOULD_CREATE_NETWORKS_IMMEDIATELY = false
+
 @RunWith(DevSdkIgnoreRunner::class)
 // NetworkAgent is not updatable in R-, so this test does not need to be compatible with older
 // versions. NetworkAgent was also based on AsyncChannel before S so cannot be tested the same way.
@@ -1208,6 +1215,7 @@
 
     @Test
     fun testUnregisterAfterReplacement() {
+        assumeFalse(Build.isDebuggable()) // Disabled presubmit pending prebuilt update on U
         // Keeps an eye on all test networks.
         val matchAllCallback = TestableNetworkCallback(timeoutMs = DEFAULT_TIMEOUT_MS)
         registerNetworkCallback(makeTestNetworkRequest(), matchAllCallback)
@@ -1247,15 +1255,15 @@
 
         // Connect a third network. Because network1 is awaiting replacement, network3 is preferred
         // as soon as it validates (until then, it is outscored by network1).
-        // The fact that the first event seen by matchAllCallback is the connection of network3
+        // The fact that the first events seen by matchAllCallback is the connection of network3
         // implicitly ensures that no callbacks are sent since network1 was lost.
         val (agent3, network3) = connectNetwork()
+        matchAllCallback.expectAvailableThenValidatedCallbacks(network3)
+        testCallback.expectAvailableDoubleValidatedCallbacks(network3)
+
         // As soon as the replacement arrives, network1 is disconnected.
         // Check that this happens before the replacement timeout (5 seconds) fires.
-        matchAllCallback.expectAvailableCallbacks(network3, validated = false)
         matchAllCallback.expect<Lost>(network1, 2_000 /* timeoutMs */)
-        matchAllCallback.expectCaps(network3) { it.hasCapability(NET_CAPABILITY_VALIDATED) }
-        testCallback.expectAvailableDoubleValidatedCallbacks(network3)
         agent1.expectCallback<OnNetworkUnwanted>()
 
         // Test lingering:
@@ -1301,8 +1309,8 @@
         val callback = TestableNetworkCallback()
         requestNetwork(makeTestNetworkRequest(specifier = specifier6), callback)
         val agent6 = createNetworkAgent(specifier = specifier6)
-        agent6.register()
-        if (SdkLevel.isAtLeastU()) {
+        val network6 = agent6.register()
+        if (SHOULD_CREATE_NETWORKS_IMMEDIATELY) {
             agent6.expectCallback<OnNetworkCreated>()
         } else {
             // No callbacks are sent, so check LinkProperties to wait for the network to be created.
@@ -1316,9 +1324,10 @@
         val timeoutMs = agent6.DEFAULT_TIMEOUT_MS.toInt() + 1_000
         agent6.unregisterAfterReplacement(timeoutMs)
         agent6.expectCallback<OnNetworkUnwanted>()
-        if (!SdkLevel.isAtLeastT() || SdkLevel.isAtLeastU()) {
+        if (!SdkLevel.isAtLeastT() || SHOULD_CREATE_NETWORKS_IMMEDIATELY) {
             // Before T, onNetworkDestroyed is called even if the network was never created.
-            // On U+, the network was created by register(). Destroying it sends onNetworkDestroyed.
+            // If immediate native network creation is supported, the network was created by
+            // register(). Destroying it sends onNetworkDestroyed.
             agent6.expectCallback<OnNetworkDestroyed>()
         }
         // Poll for LinkProperties becoming null, because when onNetworkUnwanted is called, the
@@ -1368,9 +1377,8 @@
 
         val (newWifiAgent, newWifiNetwork) = connectNetwork(TRANSPORT_WIFI)
         testCallback.expectAvailableCallbacks(newWifiNetwork, validated = true)
-        matchAllCallback.expectAvailableCallbacks(newWifiNetwork, validated = false)
+        matchAllCallback.expectAvailableThenValidatedCallbacks(newWifiNetwork)
         matchAllCallback.expect<Lost>(wifiNetwork)
-        matchAllCallback.expectCaps(newWifiNetwork) { it.hasCapability(NET_CAPABILITY_VALIDATED) }
         wifiAgent.expectCallback<OnNetworkUnwanted>()
     }
 
@@ -1478,10 +1486,10 @@
 
     @Test
     fun testNativeNetworkCreation_PhysicalNetwork() {
-        // On T and below, the native network is only created when the agent connects.
-        // Starting in U, the native network is created as soon as the agent is registered.
-        doTestNativeNetworkCreation(expectCreatedImmediately = SdkLevel.isAtLeastU(),
-            intArrayOf(TRANSPORT_CELLULAR))
+        assumeFalse(Build.isDebuggable()) // Disabled presubmit pending prebuilt update on U
+        doTestNativeNetworkCreation(
+                expectCreatedImmediately = SHOULD_CREATE_NETWORKS_IMMEDIATELY,
+                intArrayOf(TRANSPORT_CELLULAR))
     }
 
     @Test
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index bb55aee..57c3acc 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -2946,24 +2946,22 @@
         if (expectLingering) {
             generalCb.expectLosing(net1);
         }
+        generalCb.expectCaps(net2, c -> c.hasCapability(NET_CAPABILITY_VALIDATED));
+        defaultCb.expectAvailableDoubleValidatedCallbacks(net2);
 
         // Make sure cell 1 is unwanted immediately if the radio can't time share, but only
         // after some delay if it can.
         if (expectLingering) {
-            generalCb.expectCaps(net2, c -> c.hasCapability(NET_CAPABILITY_VALIDATED));
-            defaultCb.expectAvailableDoubleValidatedCallbacks(net2);
             net1.assertNotDisconnected(TEST_CALLBACK_TIMEOUT_MS); // always incurs the timeout
             generalCb.assertNoCallback();
             // assertNotDisconnected waited for TEST_CALLBACK_TIMEOUT_MS, so waiting for the
             // linger period gives TEST_CALLBACK_TIMEOUT_MS time for the event to process.
             net1.expectDisconnected(UNREASONABLY_LONG_ALARM_WAIT_MS);
-            generalCb.expect(LOST, net1);
         } else {
             net1.expectDisconnected(TEST_CALLBACK_TIMEOUT_MS);
-            generalCb.expect(LOST, net1);
-            generalCb.expectCaps(net2, c -> c.hasCapability(NET_CAPABILITY_VALIDATED));
-            defaultCb.expectAvailableDoubleValidatedCallbacks(net2);
         }
+        net1.disconnect();
+        generalCb.expect(LOST, net1);
 
         // Remove primary from net 2
         net2.setScore(new NetworkScore.Builder().build());