A QOS (Quality Of Service) error in the event log means that A packet has been lost on the ACE connection. 1 or 2 of these errors occasionally is nothing to really worry about you will probably not notice anything different with the system. If you have lots of these errors regularly you should probably get this resolved and you will be noticing glitches in the audio and possible the control of the system.
The most common causes of this problem are: Badly crimped RJ45 connectors Damaged Ethernet cable using a cable that has not been unwound from the reel interference from other power sources near your ACE cable
Try using a shorter different cable to see if this resolves the issue.
How good is this forum guys! I had an answer while I was still at the gig! Many thanks for those answers. Just incidentally, I also had a strange buzz that came and went over the Main front of house system. I was attempting to isolate the problem and noticed a massive buzz whenever the ace link cable was connected between surface and mix rack and also when my r72 surface Was connected to certain power supply sockets. I did not think it was possible to get an earth buzz on this system. It's probably part of the cable QOS thing. Bad power in the venue maybe. Jim
R72 & IDR32 MacBook pro iPad 2 Airport express router