diff --git a/experimental/libbox/monitor.go b/experimental/libbox/monitor.go
index 45b11c46d..d1f8f9387 100644
--- a/experimental/libbox/monitor.go
+++ b/experimental/libbox/monitor.go
@@ -15,9 +15,10 @@ var (
 
 type platformDefaultInterfaceMonitor struct {
 	*platformInterfaceWrapper
-	logger       logger.Logger
-	callbacks    list.List[tun.DefaultInterfaceUpdateCallback]
-	myInterfaces []string
+	logger                      logger.Logger
+	callbacks                   list.List[tun.DefaultInterfaceUpdateCallback]
+	myInterfaces                []string
+	defaultInterfaceInitialized bool
 }
 
 func (m *platformDefaultInterfaceMonitor) Start() error {
@@ -77,6 +78,7 @@ func (m *platformDefaultInterfaceMonitor) updateDefaultInterface(interfaceName s
 	m.defaultInterfaceAccess.Lock()
 	if interfaceIndex32 == -1 {
 		m.defaultInterface = nil
+		m.defaultInterfaceInitialized = true
 		callbacks := m.callbacks.Array()
 		m.defaultInterfaceAccess.Unlock()
 		for _, callback := range callbacks {
@@ -92,10 +94,11 @@ func (m *platformDefaultInterfaceMonitor) updateDefaultInterface(interfaceName s
 		return
 	}
 	m.defaultInterface = newInterface
-	if oldInterface != nil && oldInterface.Name == m.defaultInterface.Name && oldInterface.Index == m.defaultInterface.Index {
+	if m.defaultInterfaceInitialized && oldInterface != nil && oldInterface.Name == m.defaultInterface.Name && oldInterface.Index == m.defaultInterface.Index {
 		m.defaultInterfaceAccess.Unlock()
 		return
 	}
+	m.defaultInterfaceInitialized = true
 	callbacks := m.callbacks.Array()
 	m.defaultInterfaceAccess.Unlock()
 	for _, callback := range callbacks {