kayakmc

I am having problems on palying on-line. 99% of the times it does not work. When I am entering in a server, into the lobby or into de game in progress, I am always being removed from the game. Some times I can play for a couple of minutes but then it says tar my router/ Nat is to strict. I dont now what to do! My pc can run it fine, but the problem seems to be from the router. Any help, is welcome! Thanks.