Multiplayer FPS Testing

Hi All

I have a question. I have a Master Server set up on my home machine, and I am using my home machine as a server also. So far I have loaded up for testing purposes the starter.fps on my machine and using it to host a multi-player game. I then took another one of my laptop's to one of my friend's home and loaded up the starter.fps using his internet connection, queried the master server, and it found the server, I clicked join the server and I seen the game running on my home computer, but when I started game play, running around, shooting, etc..... It lost connection,could anyone tell me what this could be.

I have verified that it can be played across the network, but the connection just drops after some initial game play.

Please help.