@rokube is it 80 devices per AP?  If so that is somewhat above the recommended maximum.  The recommendations for reasonable service are 30 devices per radio, so if they are evenly distributed between the 2.4GHz and 5GHz radios, then you can get 60.  It is true that if most devices are only low usage then you can have more, but there is no guarantee of decent service.  Another thing to consider is how many SSIDs are broadcasting on each radio, ideally no more than three should be as each additional one uses more of the shared timeslots.  Finally, what do you have the minimum bitrate set to, anything less than 12 enables 802.11b and the associated slower multiplexing which will affect all clients.   In terms of diagnostics, have you enabled "AP neighbours" in the early access section?  That can show you which APs are struggling with packet loss etc. as below:       ... View more