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Although it's not an ideal solution, scheduling a reboot of the AP during off-hours can help clear all connections and refresh the system. This can be done through the UniFi Controller's settings.
Deploy More APs
Increasing the number of access points will help distribute the load, preventing any single AP from being overwhelmed with connections.
In Securaze Dashboard / Settings it’s possible to define multiple WiFi connections and for each Mobile station a different Wifi connection can be setup.