Investigating Unifi UAC AP Lite errors on Wifi interfaces
Solution 1:
Gather more information
Look at the UniFi control panel. You should find some useful statistics under the Wi-Fi Metrics dashboard:
- Anomalies
- Association failures - does one failure type appear particularly often?
- Access point retry rate - do specific APs have significantly more retries?
Also take a look at connected devices. See if any have particularly poor signal strength. Even consider manually forcing a reconnect (you can do that in the control panel) and see which AP they choose to connect to - is it a better one? This will inform you which steps you should take next.
High-density deployments
Sometimes, having a super-dense deployment is a bad thing. At certain levels, APs start interfering with each other. Also, devices may connect to suboptimal APs and roam incorrectly.
You should read UniFi - High Density WLAN Scenario Guide. Pay particular attention to the Design section, where they address cell sizing.
Tuning cell sizes and signal strength
You should consider reducing signal strength as much as possible, to reduce interference and overlap. Ideally each AP does not overlap with more than its immediate neighbours.
You may wish to remove some APs to give them more breathing room.
You may wish to set up a minimum RSSI to kick clients that have a poor connection, in the hopes that they connect to a more appropriate AP. This helps force stubborn clients to roam to a closer AP rather than remaining connected to a poor, far-away, one.
Consider tuning 2.4 GHz transmit power as low as possible, and maybe even turning off the 2.4 GHz radio on adjacent APs, as there are very limited channels (3 non-overlapping, total!) available and 2.4 GHz signals propagate relatively far. Hopefully most client devices you're dealing with support 5 GHz.
Consider reducing bandwidth - a 20 MHz bandwidth is likely sufficient for public internet access at short distance from the AP. This wastes fewer channels than 40 or 80 MHz widths, giving you more chance at avoiding overlap/noise.
Depending on your layout, you may wish to assign channels manually so overlapping APs do not use adjacent (or, worse, same) channels. Auto-channel selection may already take care of this. Use measurement/graphing tools to find out.
All of this is described in the design and cell sizing section of the Ubiquiti document.
Use signal measurement tools
There are various tools available that can measure and graph signal levels visible to a client device. Ubiquiti themselves have WiFiman, available as both an iOS and Android app.
Use one to measure signal strength in each of your locations. Ideally you want one strong signal per non-overlapping channel, so you should tune your signal strengths to achieve this result. Situations where you have either no strong signals, or many strong signals (= noise) are suboptimal and may result in degraded experiences.