the games keep lagging out

Why can't you try a direct modem connection? That's really going to be the only way to determine if it's an issue in the router, or an issue with your service. I would also recommend testing a different ethernet cable as well.

I have seen this problem as well myself quite a bit in various multiplayer games when in a party chat. I always assumed it was the settings/connection of one or more of the other people, something related to voice/chat on the network in general, or a
problem with a game and a separate party chat going on at once.

So it would be interesting to see if there is some sort of a fix for this that would benefit everyone in a party regardless of how good (or bad) everyone's individual connection is.

Well UPnP is out, it worked then crashed my whole network. Turned it off and everything worked fine.

if you are using wireless this happened to me a lot until i moved my 360 closer to the router

It lags for about 10 seconds so it would be hard to catch it while it's happening. I took these right before I started playing, I played for about a hour and "lagged" out probably 5 times. It lagged while I was playing gears of war with a friend, I was removed
from the party and in the game the characters around me would just walk straight. Once the lag stopped they game resumed and I'd reconnect to the party or I was put in my own. Also the second test is an A with a ping at 24ms with a 3ms jitter.