Unifi USG Pro high cpu usage

[caffrey]

I've had an issue with our unifi setup for a while, with clients struggling to get IPs etc. I think I've traced the issue and it's down to high CPU usage on the USG pro related to DNSMasq and Avahi-daemon. First thing in the morning with a few clients on there is very little cpu usage, but as soon as students arrive DNSMasq hits 70-80% cpu and avahi was competing with cpu cycles too. I moved avahi to a Raspberry pi to alleviate the problem but it hasn't helped, in fact the avahi-daemon on the Rpi is mirroring the cpu usage it was using on the USG.

Also on the USG, the hosts file has over 4000 entries... Not sure if it's worth clearing that out

 

We have a lot of BYOD, and I'm starting to wonder if there is something wrong or untoward with a student device but I've no idea how to trace it . It seems to ramp up at random times of the day

 

Just throwing this out there in case anyone has a better clue than me If I can get to the bottom of this the wifi will be fixed and I can stop moaning about unifi

[Layers]

We are running an almost all Unifi at our district, experiencing almost identical symptoms with our USG Pro 4 Router. Did you ever find a solution? At this point we are looking to swap the Pro 4 for a Dream Machine, but did not know if there was another out. So far we have reduced the load on the USG pro as much as we could, but symptoms persist.