Connection interrupted - MAX_PACKET_USERCMDS

[oAaRD]

Hi, OpenArena community!
I've downloaded 0.8.1 and applied 0.8.5 against it (fresh install). I successfully can connect to any server from list, but this weird flicker connection interrupts are very awful, I can't play at all! On console I see only "MAX_PACKET_USERCMDS", continuously. Firewall is restricted, but allows OpenArena ports (worked perfect with <=0.8.1). Tested on local server - I get MAX_PACKET_USERCMDS, but rarely and no connection interrupts.
Config: Linux 2.6 (x86_64), OA 0.8.5.
Please, can you help me?

[andrewj]

Does it happen when you turn off the firewall?

[oAaRD]

Does it happen when you turn off the firewall?

Now it is not so possible to just turn off the firewall. Firewall is my router+server, so if I just turn it off, I will break many things and I will allow anything usually not allowed. And a machine I playing from is behind this router, I also playing Nexuiz normally (using 26000 udp port number), I see no problem here for other games. I doublechecked iptables logs for any rejected traffic - no results. Did capture - all fine, no rejects or other anomaly.
I recently noticed that "Connection interrupted" and flooding happens in closed areas and when using portals. I can shoot (I hear bullet sounds), but can't move.
Hm, maybe this is just an ISP issue? When I create local server on local network behind router and apply same firewall rules - anything works perfect.

UPD: Discovered that this happens only when ping greater than 150-200.