Problem with online gaming

[db]

I have a home network with 2 pcs, running WinGate 5.2.3

The problem is with a half-life mod we play online. If I connect to a server first (wingate server running on my machine), then the client pc can connect and play fine with no problems, we both play away happily.

however if the client pc joins a server first, then I try to join, she gets disconnected from the server, and my pc 'hangs' on 'connecting to server'

is there some special way I need to set something up so that it doesnt matter who joins first?

[db]

anyone? with any ideas at all? :/