What ports have to be open on a firewall to allow me to play multiplayer games?
You will likely experience difficulty in using Arcade or playing games if you are behind a firewall or a similarly restrictive proxy server. Arcade and the multiplayer modes of supported games can be used only if certain data is free to travel back and forth across your Internet connection. If your firewall is set to restrict access, Arcade cannot verify information in its database, send you the chat responses from other users, nor send you the game server lists. Arcade was certainly not designed to work around your firewall! Since there are many, many different types of firewalls and network environments, our tech support information cannot guide you with each one. Check your firewall’s security settings, or contact your administrator. If you are behind a firewall and are able to change its settings, Arcade needs the following ports open in order to function (more ports might also be necessary in order to run certain games). Unless specified otherwise, the TCP ports are: 6667 (IRC) 80
