diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index 07fce08..bb9b6fb 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -1533,16 +1533,28 @@
         return mConfig;
     }
 
-    boolean hasTetherableConfiguration() {
-        final TetheringConfiguration cfg = mConfig;
-        final boolean hasDownstreamConfiguration =
-                (cfg.tetherableUsbRegexs.length != 0)
-                || (cfg.tetherableWifiRegexs.length != 0)
-                || (cfg.tetherableBluetoothRegexs.length != 0);
-        final boolean hasUpstreamConfiguration = !cfg.preferredUpstreamIfaceTypes.isEmpty()
-                || cfg.chooseUpstreamAutomatically;
+    boolean hasAnySupportedDownstream() {
+        if ((mConfig.tetherableUsbRegexs.length != 0)
+                || (mConfig.tetherableWifiRegexs.length != 0)
+                || (mConfig.tetherableBluetoothRegexs.length != 0)) {
+            return true;
+        }
 
-        return hasDownstreamConfiguration && hasUpstreamConfiguration;
+        // Before T, isTetheringSupported would return true if wifi, usb and bluetooth tethering are
+        // disabled (whole tethering settings would be hidden). This means tethering would also not
+        // support wifi p2p, ethernet tethering and mirrorlink. This is wrong but probably there are
+        // some devices in the field rely on this to disable tethering entirely.
+        if (!SdkLevel.isAtLeastT()) return false;
+
+        return (mConfig.tetherableWifiP2pRegexs.length != 0)
+                || (mConfig.tetherableNcmRegexs.length != 0)
+                || isEthernetSupported();
+    }
+
+    // TODO: using EtherentManager new API to check whether ethernet is supported when the API is
+    // ready to use.
+    private boolean isEthernetSupported() {
+        return mContext.getSystemService(Context.ETHERNET_SERVICE) != null;
     }
 
     void setUsbTethering(boolean enable, IIntResultListener listener) {
@@ -2463,7 +2475,7 @@
         final boolean tetherEnabledInSettings = tetherSupported
                 && !mUserManager.hasUserRestriction(UserManager.DISALLOW_CONFIG_TETHERING);
 
-        return tetherEnabledInSettings && hasTetherableConfiguration()
+        return tetherEnabledInSettings && hasAnySupportedDownstream()
                 && !isProvisioningNeededButUnavailable();
     }
 
diff --git a/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
index c1a747e..9224213 100644
--- a/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
+++ b/Tethering/src/com/android/networkstack/tethering/TetheringDependencies.java
@@ -94,13 +94,6 @@
     public abstract IpServer.Dependencies getIpServerDependencies();
 
     /**
-     * Indicates whether tethering is supported on the device.
-     */
-    public boolean isTetheringSupported() {
-        return true;
-    }
-
-    /**
      * Get a reference to the EntitlementManager to be used by tethering.
      */
     public EntitlementManager getEntitlementManager(Context ctx, Handler h, SharedLog log,
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 e4dbc7d..8acbb8a 100644
--- a/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
+++ b/Tethering/tests/unit/src/com/android/networkstack/tethering/TetheringTest.java
@@ -297,6 +297,7 @@
     private TetheredInterfaceCallbackShim mTetheredInterfaceCallbackShim;
 
     private TestConnectivityManager mCm;
+    private boolean mForceEthernetServiceUnavailable = false;
 
     private class TestContext extends BroadcastInterceptingContext {
         TestContext(Context base) {
@@ -331,7 +332,11 @@
             if (Context.USER_SERVICE.equals(name)) return mUserManager;
             if (Context.NETWORK_STATS_SERVICE.equals(name)) return mStatsManager;
             if (Context.CONNECTIVITY_SERVICE.equals(name)) return mCm;
-            if (Context.ETHERNET_SERVICE.equals(name)) return mEm;
+            if (Context.ETHERNET_SERVICE.equals(name)) {
+                if (mForceEthernetServiceUnavailable) return null;
+
+                return mEm;
+            }
             return super.getSystemService(name);
         }
 
@@ -452,11 +457,6 @@
         }
 
         @Override
-        public boolean isTetheringSupported() {
-            return true;
-        }
-
-        @Override
         public TetheringConfiguration generateTetheringConfiguration(Context ctx, SharedLog log,
                 int subId) {
             mConfig = spy(new FakeTetheringConfiguration(ctx, log, subId));
@@ -680,6 +680,7 @@
                 .thenReturn(new String[] {TEST_BT_REGEX});
         when(mResources.getStringArray(R.array.config_tether_ncm_regexs))
                 .thenReturn(new String[] {TEST_NCM_REGEX});
+        when(mPackageManager.hasSystemFeature(PackageManager.FEATURE_ETHERNET)).thenReturn(true);
         when(mResources.getIntArray(R.array.config_tether_upstream_types)).thenReturn(
                 new int[] {TYPE_WIFI, TYPE_MOBILE_DUN});
         when(mResources.getBoolean(R.bool.config_tether_upstream_automatic)).thenReturn(true);
@@ -2834,6 +2835,55 @@
         runDualStackUsbTethering(TEST_RNDIS_IFNAME);
         runStopUSBTethering();
     }
+
+    @Test
+    public void testTetheringSupported() throws Exception {
+        setTetheringSupported(true /* supported */);
+        updateConfigAndVerifySupported(true /* supported */);
+
+        // Could disable tethering supported by settings.
+        Settings.Global.putInt(mContentResolver, Settings.Global.TETHER_SUPPORTED, 0);
+        updateConfigAndVerifySupported(false /* supported */);
+
+        // Could disable tethering supported by user restriction.
+        setTetheringSupported(true /* supported */);
+        when(mUserManager.hasUserRestriction(
+                UserManager.DISALLOW_CONFIG_TETHERING)).thenReturn(true);
+        updateConfigAndVerifySupported(false /* supported */);
+
+        // Tethering is supported if it has any supported downstream.
+        setTetheringSupported(true /* supported */);
+        when(mResources.getStringArray(R.array.config_tether_usb_regexs))
+                .thenReturn(new String[0]);
+        updateConfigAndVerifySupported(true /* supported */);
+        when(mResources.getStringArray(R.array.config_tether_wifi_regexs))
+                .thenReturn(new String[0]);
+        updateConfigAndVerifySupported(true /* supported */);
+
+
+        if (isAtLeastT()) {
+            when(mResources.getStringArray(R.array.config_tether_bluetooth_regexs))
+                    .thenReturn(new String[0]);
+            updateConfigAndVerifySupported(true /* supported */);
+            when(mResources.getStringArray(R.array.config_tether_wifi_p2p_regexs))
+                    .thenReturn(new String[0]);
+            updateConfigAndVerifySupported(true /* supported */);
+            when(mResources.getStringArray(R.array.config_tether_ncm_regexs))
+                    .thenReturn(new String[0]);
+            updateConfigAndVerifySupported(true /* supported */);
+            mForceEthernetServiceUnavailable = true;
+            updateConfigAndVerifySupported(false /* supported */);
+        } else {
+            when(mResources.getStringArray(R.array.config_tether_bluetooth_regexs))
+                    .thenReturn(new String[0]);
+            updateConfigAndVerifySupported(false /* supported */);
+        }
+    }
+
+    private void updateConfigAndVerifySupported(boolean supported) {
+        sendConfigurationChanged();
+        assertEquals(supported, mTethering.isTetheringSupported());
+    }
     // TODO: Test that a request for hotspot mode doesn't interfere with an
     // already operating tethering mode interface.
 }