WAC540 not connecting to devices

Randomly WAC540 dropps connection the it will not allow devices to connect. I can log on via the LAN and access the AP. it tells me i have internet connection but all device will not connect to any SSID (i have 2)  or ro any band. I have rebooted, i disconnect and i have factory reset and re-configured th e AP. it works for a while then does it again. I am running firmware version V9.9.1.3. any guidance? this is for my home network as my wife and I work from home.