Routor problem is when both pc,s enter same mohaa server within secounds or 2 to 3 mins max game locks up both work fine browsing web. im kinda revisiting ths problem as 6 mths ago i spent a lot of time on the phone to belkin,they even sent a new router out free of charge nice but that didnt solve the issue ether. both pc,s on xp internet provider is vergin aka ntl 20meg service router is wired connection 4 port well heres hopeing thanks

I think that the service that you are tring to use is having to use something called port mapping or (UPnP)

e.g

PC1 using IP = 192.168.1.4 using port 123
PC2 using IP = 192.168.1.5 using port 123
Router using IP = 192.168.1.1 can only map one port 123 at one time.

On the games try to use a different port, or like up port redirection on google which should put you to the right direction.

Hope this makes sence and is usefull.

Best of luck.