Starcraft 2 chat problem with multiple players on same connection

The in-game voice works fine for me but if I have friends come over and we're all on the same connection, only one of us can use voice chat. Everyone else appears to be muted.

Could this have something to do with my firewall settings? Do I need to forward any ports? Would that even help since there's multiple people on the same connection?

Solution 1:

SC2 voice chat does not support NAT for multiple end point connections from a LAN, so the first one to connect claims the connection exclusively, the following clients get nothing.

In short, it's broken. Use something else. Skype works wonderfully, as Ventrilo or Teamspeak do.