Receiving NAT punchthrough attempt from target 684547167205435679 failed..

hello I have a game with multiplayer but now when a clients joins I get this error:
“Receiving NAT punchthrough attempt from target 684547167205435679 failed”

When I launch a server is use this:
var useNat = !Network.HavePublicAddress();
-Network.InitializeServer(GameMaxPlayers-1, 8935, useNat);

-MasterServer.RegisterHost(GameMode,GameName,“”);

When connecting I use this:
-Network.Connect(element);

I’m not sure if this is the problem but make sure the appropriate ports are open in your router.