Problem's in the title.
Router - TL-WR1043ND (TP-Link), latest firmware.
Wireless security - WPA2/AES.
OS - OpenSuSE 12.2 and 12.1 (two computers).
After reboot everything is fine, after high net load (I think) it slows down and router admin becomes unavailable, although internet is still reachable, just VERY slow...