Right now I suspect Crysis 2 to send too many ping requests for my router to cope with. It drops the connection completely if too many servers are listed in the Crysis 2 browser. Now I agree that the router is bad and should be replaced, however it is the router provided for a larger ISP in Austria so it's probably deployed in quite a lot of households.
I suppose it would make sense to only ping a handful of servers and then send more requests if the queued finished. Maybe something else is at fault there, but the most likely explanation I could come up with is that the NAT table overflows.
Maybe that could be investigated for the next patch.