diff --git a/net/netmon/defaultroute_bsd.go b/net/netmon/defaultroute_bsd.go
index b66a84636..9195ae073 100644
--- a/net/netmon/defaultroute_bsd.go
+++ b/net/netmon/defaultroute_bsd.go
@@ -1,11 +1,11 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-// Common code for FreeBSD and Darwin. This might also work on other
+// Common code for FreeBSD. This might also work on other
 // BSD systems (e.g. OpenBSD) but has not been tested.
-// Not used on iOS. See defaultroute_ios.go.
+// Not used on iOS or macOS. See defaultroute_darwin.go.
 
-//go:build !ios && (darwin || freebsd)
+//go:build freebsd
 
 package netmon
 
diff --git a/net/netmon/defaultroute_ios.go b/net/netmon/defaultroute_darwin.go
similarity index 59%
rename from net/netmon/defaultroute_ios.go
rename to net/netmon/defaultroute_darwin.go
index 63d5e49ce..9da52e311 100644
--- a/net/netmon/defaultroute_ios.go
+++ b/net/netmon/defaultroute_darwin.go
@@ -1,12 +1,13 @@
 // Copyright (c) Tailscale Inc & AUTHORS
 // SPDX-License-Identifier: BSD-3-Clause
 
-//go:build ios
+//go:build darwin || ios
 
 package netmon
 
 import (
 	"log"
+	"net"
 
 	"tailscale.com/syncs"
 )
@@ -22,12 +23,12 @@ func UpdateLastKnownDefaultRouteInterface(ifName string) {
 		return
 	}
 	if old := lastKnownDefaultRouteIfName.Swap(ifName); old != ifName {
-		log.Printf("defaultroute_ios: update from Swift, ifName = %s (was %s)", ifName, old)
+		log.Printf("defaultroute_darwin: update from Swift, ifName = %s (was %s)", ifName, old)
 	}
 }
 
 func defaultRoute() (d DefaultRouteDetails, err error) {
-	// We cannot rely on the delegated interface data on iOS. The NetworkExtension framework
+	// We cannot rely on the delegated interface data on darwin. The NetworkExtension framework
 	// seems to set the delegate interface only once, upon the *creation* of the VPN tunnel.
 	// If a network transition (e.g. from Wi-Fi to Cellular) happens while the tunnel is
 	// connected, it will be ignored and we will still try to set Wi-Fi as the default route
@@ -37,16 +38,13 @@ func defaultRoute() (d DefaultRouteDetails, err error) {
 	// the interface name of the first currently satisfied network path. Our Swift code will
 	// call into `UpdateLastKnownDefaultRouteInterface`, so we can rely on that when it is set.
 	//
-	// If for any reason the Swift machinery didn't work and we don't get any updates, here
-	// we also have some fallback logic: we try finding a hardcoded Wi-Fi interface called en0.
-	// If en0 is down, we fall back to cellular (pdp_ip0) as a last resort. This doesn't handle
-	// all edge cases like USB-Ethernet adapters or multiple Ethernet interfaces, but is good
-	// enough to ensure connectivity isn't broken.
+	// If for any reason the Swift machinery didn't work and we don't get any updates, we will
+	// fallback to the BSD logic.
 
 	// Start by getting all available interfaces.
 	interfaces, err := netInterfaces()
 	if err != nil {
-		log.Printf("defaultroute_ios: could not get interfaces: %v", err)
+		log.Printf("defaultroute_darwin: could not get interfaces: %v", err)
 		return d, ErrNoGatewayIndexFound
 	}
 
@@ -57,13 +55,13 @@ func defaultRoute() (d DefaultRouteDetails, err error) {
 			}
 
 			if !ifc.IsUp() {
-				log.Printf("defaultroute_ios: %s is down", name)
+				log.Printf("defaultroute_darwin: %s is down", name)
 				return nil
 			}
 
 			addrs, _ := ifc.Addrs()
 			if len(addrs) == 0 {
-				log.Printf("defaultroute_ios: %s has no addresses", name)
+				log.Printf("defaultroute_darwin: %s has no addresses", name)
 				return nil
 			}
 			return &ifc
@@ -79,30 +77,22 @@ func defaultRoute() (d DefaultRouteDetails, err error) {
 		if ifc != nil {
 			d.InterfaceName = ifc.Name
 			d.InterfaceIndex = ifc.Index
+			log.Printf("defaultroute_darwin: using lastKnownDefaultRouteInterface %s %v", d.InterfaceName, d.InterfaceIndex)
 			return d, nil
 		}
 	}
 
-	// Start of our fallback logic if Swift didn't give us an interface name, or gave us an invalid
-	// one.
-	// We start by attempting to use the Wi-Fi interface, which on iPhone is always called en0.
-	enZeroIf := getInterfaceByName("en0")
-	if enZeroIf != nil {
-		log.Println("defaultroute_ios: using en0 (fallback)")
-		d.InterfaceName = enZeroIf.Name
-		d.InterfaceIndex = enZeroIf.Index
-		return d, nil
+	// Fallback to the BSD logic
+	idx, err := DefaultRouteInterfaceIndex()
+	if err != nil {
+		return d, err
 	}
-
-	// Did it not work? Let's try with Cellular (pdp_ip0).
-	cellIf := getInterfaceByName("pdp_ip0")
-	if cellIf != nil {
-		log.Println("defaultroute_ios: using pdp_ip0 (fallback)")
-		d.InterfaceName = cellIf.Name
-		d.InterfaceIndex = cellIf.Index
-		return d, nil
+	iface, err := net.InterfaceByIndex(idx)
+	if err != nil {
+		return d, err
 	}
-
-	log.Println("defaultroute_ios: no running interfaces available")
-	return d, ErrNoGatewayIndexFound
+	d.InterfaceName = iface.Name
+	d.InterfaceIndex = idx
+	log.Printf("defaultroute_darwin: using table dervied default if %s %v", d.InterfaceName, d.InterfaceIndex)
+	return d, nil
 }