Freelancer MP server problem

A friend of mine running a Freelancer server is having a problem with other players’ connectivity. Basically, everyone else but himself can stay on it for about 5 minutes, then lose connection. He has upgraded the firmware on his router but is still having the same problem. I’ve checked some other Freelancer sites to see if anyone else is having the problem but it seems that no one else is. Since there’s a lot of techie people here that may have an idea, I decided to post this here. Any suggestions?

Ensure that the ports referenced in the readme file are opened.