In Battlefield 3, I'm able to connect to a server with a first computer, but the second computer in the LAN will always keep on the "connecting..." phase. I think that happens because I was using the same port.
Origin uses registry to launch the game so I changed the registry to use another port:
C:\Program Files (x86)\Origin Games\Battlefield 3\bf3.exe +clientport 20000
But it didn't work. Also tried to enable/disable UPnP.
Of course both computers have different accounts.