I used my UR22MKII for a couple of months fighting with drop outs in BIOS. Then I completely reinstalled LAN drivers on my MOBO and since then I have not noticed any issues. I have tried stressing the system with AIDA 64, opening a few youtube instances, starting MP Classic, launching Cubase 7.5 at the same time 
- no problems occurred. Have not experienced any drop outs for a couple of days, though. Hope it can help. 
Two weeks gone. The problem retuns. 