The best place to look it on the forum section dedicated to it on the steam forums.
Also my uni blocks the ports for Killing Floor, so I have to play around in SP QQ. And easy in KF is probably the easiest easy I've ever tried out. Like seriously I just had the AA12 for the final boss on farm, and just spammed one clip into him and he was dead.
I had this same exact problem with killing floor for a while. I only joined games hosted by my friend, and I would lag out in his games but other players wouldn't. When I joined games hosted by other people it didn't happen to me. Have you tried playing with different hosts?