Returns the public IP address and port of the current server. This will return the IP/port that you are connecting through when ran clientside.
Returns "0.0.0.0:0" in singleplayer.
Returns "0.0.0.0:port" on the server when called too early, including in GM:Initialize and GM:InitPostEntity. This bug seems to only happen the first time a server is launched, and will return the correct value after switching maps.
Issue Tracker: #3001