I don't know if anyone is able to help but I've had a lot of problems playing games via steam. I find the other players jump and my connection freezes for a split second. I've been following the advice of the MTU sticky and I've now got my connection better than ever but for this one small problem.
In addition when playing my latency jumps from a small value like 60 to a large value like 1200 and back again.
I don't seem to get any problems, playing any other on-line games.