RCadmin,
If you could use the multiplayer for a minute or two, it should not the gateway router. If it was, you would not have made a connection at all. It would have blocked the original connection. Chances are, the issue is elsewhere...
Just a note; When I used my Netgear 314(?) with HalfLife/TFC/Counter Strike, the latency was higher than without it. Therefor, the router was adding a bit of latency for processing time. This should not affect connection stability, just speed.
Later, Jason