network: minor fix in switch_to_interface

electrum/interface.py

@@ -212,7 +212,7 @@ class Interface(PrintError):
         try:
             await self.open_session(ssl_context, exit_early=False)
         except (asyncio.CancelledError, OSError, aiorpcx.socks.SOCKSFailure) as e:
-            self.print_error('disconnecting due to: {}'.format(e))
+            self.print_error('disconnecting due to: {} {}'.format(e, type(e)))
             self.exception = e
             return
         # should never get here (can only exit via exception)

electrum/network.py

@@ -569,9 +569,10 @@ class Network(PrintError):
                 # and to cancel tasks in interface.group.
                 # However, for headers sub, give preference to this interface
                 # over unknown ones, i.e. start it again right away.
+                old_server = self.interface.server
                 self.close_interface(self.interface)
                 if len(self.interfaces) <= self.num_server:
-                    self.start_interface(self.interface.server)
+                    self.start_interface(old_server)
 
             self.interface = i
             asyncio.get_event_loop().create_task(