Issue with Halo

[DarkHououmon]

Edit: Okay, rewriting this post because the original was sloppy.

The issue I am having is not strictly Halo; MSN games and any Multiplayer games don't work very well for me if I were to try and play against someone else. I can create rooms just fine. But I am not able to play against a friend. MSN games just keep on loading forever and never get completed. And Multiplayer games, I am not able to join any room a friend of mine makes, nor are they able to join mine. Half the time, they don't even see my rooms.

But what baffles me is that I am able to join any room that's in the list, like with Halo. I can pick any open game in the list and join it just fine. But when it comes to joining a room a specific person makes, I cannot join. It keeps telling me it's retrying the server, and then evetually it just kicks me out, unable to sign me in.

I thought it was my router at first, but I'm not sure if that is the only reason, since it only effects me if I'm trying to join specific rooms set up by someone I know; it doesn't block me from joining the other games. Although the problems did arise sometime after I got the router set up, so maybe it is the router causing it.

Does anyone know of anyway for me to fix this?