High Pingspikes to certain people

[Mephi]

Hey,
i have this problem since a few days, if i play a teamgame i have pings around the 100 mark to one group of players, to the other group i have high ping spikes, 1.5k+, while first group stays green and fine. It is not on their side its on mine thats for sure, because they dont have the spikes to other players except me. I think it may be caused by the proxy connection between me and others, but i am not sure about it.

Any ideas?

Edit:
A quick test with keyser(only us 2) was fine even with proxy. But in a teamgame i had the upper problem with him.