diff --git a/wgengine/monitor/monitor.go b/wgengine/monitor/monitor.go
index 9f8610a06..da99a9d6c 100644
--- a/wgengine/monitor/monitor.go
+++ b/wgengine/monitor/monitor.go
@@ -148,6 +148,20 @@ func (m *Mon) Close() error {
 	return err
 }
 
+// InjectEvent forces the monitor to pretend there was a network
+// change and re-check the state of the network. Any registered
+// ChangeFunc callbacks will be called within the event coalescing
+// period (under a fraction of a second).
+func (m *Mon) InjectEvent() {
+	select {
+	case m.change <- struct{}{}:
+	default:
+		// Another change signal is already
+		// buffered. Debounce will wake up soon
+		// enough.
+	}
+}
+
 func (m *Mon) stopped() bool {
 	select {
 	case <-m.stop:
@@ -175,13 +189,7 @@ func (m *Mon) pump() {
 		if msg.ignore() {
 			continue
 		}
-		select {
-		case m.change <- struct{}{}:
-		default:
-			// Another change signal is already
-			// buffered. Debounce will wake up soon
-			// enough.
-		}
+		m.InjectEvent()
 	}
 }
 
diff --git a/wgengine/monitor/monitor_test.go b/wgengine/monitor/monitor_test.go
index f1e35439e..9dd012ded 100644
--- a/wgengine/monitor/monitor_test.go
+++ b/wgengine/monitor/monitor_test.go
@@ -7,6 +7,7 @@ package monitor
 import (
 	"flag"
 	"testing"
+	"time"
 
 	"tailscale.com/net/interfaces"
 )
@@ -32,6 +33,29 @@ func TestMonitorJustClose(t *testing.T) {
 	}
 }
 
+func TestMonitorInjectEvent(t *testing.T) {
+	mon, err := New(t.Logf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer mon.Close()
+	got := make(chan bool, 1)
+	mon.RegisterChangeCallback(func(changed bool, state *interfaces.State) {
+		select {
+		case got <- true:
+		default:
+		}
+	})
+	mon.Start()
+	mon.InjectEvent()
+	select {
+	case <-got:
+		// Pass.
+	case <-time.After(5 * time.Second):
+		t.Fatal("timeout waiting for callback")
+	}
+}
+
 var monitor = flag.String("monitor", "", `go into monitor mode like 'route monitor'; test never terminates. Value can be either "raw" or "callback"`)
 
 func TestMonitorMode(t *testing.T) {
diff --git a/wgengine/userspace.go b/wgengine/userspace.go
index d61b9645d..8d73e9483 100644
--- a/wgengine/userspace.go
+++ b/wgengine/userspace.go
@@ -1251,6 +1251,12 @@ func (e *userspaceEngine) GetLinkMonitor() *monitor.Mon {
 	return e.linkMon
 }
 
+// LinkChange signals a network change event. It's currently
+// (2021-03-03) only called on Android.
+func (e *userspaceEngine) LinkChange(_ bool) {
+	e.linkMon.InjectEvent()
+}
+
 func (e *userspaceEngine) linkChange(changed bool, cur *interfaces.State) {
 	up := cur.AnyInterfaceUp()
 	if !up {
diff --git a/wgengine/watchdog.go b/wgengine/watchdog.go
index bcef4e160..3b96f2e8e 100644
--- a/wgengine/watchdog.go
+++ b/wgengine/watchdog.go
@@ -99,6 +99,9 @@ func (e *watchdogEngine) SetNetInfoCallback(cb NetInfoCallback) {
 func (e *watchdogEngine) RequestStatus() {
 	e.watchdog("RequestStatus", func() { e.wrap.RequestStatus() })
 }
+func (e *watchdogEngine) LinkChange(isExpensive bool) {
+	e.watchdog("LinkChange", func() { e.wrap.LinkChange(isExpensive) })
+}
 func (e *watchdogEngine) SetDERPMap(m *tailcfg.DERPMap) {
 	e.watchdog("SetDERPMap", func() { e.wrap.SetDERPMap(m) })
 }
diff --git a/wgengine/wgengine.go b/wgengine/wgengine.go
index a72d0a96a..57bc7cb77 100644
--- a/wgengine/wgengine.go
+++ b/wgengine/wgengine.go
@@ -89,6 +89,21 @@ type Engine interface {
 	// TODO: return an error?
 	Wait()
 
+	// LinkChange informs the engine that the system network
+	// link has changed.
+	//
+	// The isExpensive parameter is not used.
+	//
+	// LinkChange should be called whenever something changed with
+	// the network, no matter how minor.
+	//
+	// Deprecated: don't use this method. It was removed shortly
+	// before the Tailscale 1.6 release when we remembered that
+	// Android doesn't use the Linux-based link monitor and has
+	// its own mechanism that uses LinkChange. Android is the only
+	// caller of this method now. Don't add more.
+	LinkChange(isExpensive bool)
+
 	// SetDERPMap controls which (if any) DERP servers are used.
 	// If nil, DERP is disabled. It starts disabled until a DERP map
 	// is configured.