Hi Darrel,
Thank you for your reply. The first thing I tried was setting the TX power to FULL, honestly I didn't see any change. I suppose AUTO is working also to FULL if there is no close interference, and I have only 3 APs, they should work on 2.4Ghz at 1,6,11 channels most of the time, and they are far enough to not interfere on 5ghz band. Can you ask your PLM to publish updated Datasheet online? If the current one is wrong, this is quite confusing. I spent some time this evening trying to position the APs in different places than before, but if the R550 azimuth antenna pattern is wrong in the datasheet this means my new position is worse than the old one! I didn't have enough time to redo Site Survey after all the repositioning today.