Router Problems with gaming

Hello I am currently using the Microsoft Wired Base Station
MN-100. I play a multiplayer, internet game called
America's Army. When I search for gaming servers I cannot
find any and I know it's because of the router. All my
settings for the game are correct I know that because I
used to be able to find tons of servers before I got the
router and now I can't find any.

I shut down the built in firewall thinking that this was
the problem, but it wasn't. I read the manual and came
across a thing called "port forwarding." Now I don't know
why I would have to configure ports because it seems
complicated and unncessary. I used to be on a different
network that I set up personally and we never had to
configure any ports.

Does anyone have this router or understand the way ports work?