network: switch lagging interface

electrum/interface.py

@@ -394,6 +394,7 @@ class Interface(PrintError):
                 # in the simple case, height == self.tip+1
                 if height <= self.tip:
                     await self.sync_until(height)
+            self.network.switch_lagging_interface()
 
     async def sync_until(self, height, next_height=None):
         if next_height is None: