It doesn't.. :} That error happens for everyone every time they exit the game, but it doesn't affect anything at all - and it's fixed in the next release. You didn't answer my questions however, a habit I'd like you to avoid.
1) Did you find anything saying "port" or "forwarding" or similar within your router setup?
2) Did you manage to ask your brother for help, or is there anyone else in your household who may be able to do this for you?