WNDAP Firmware - Freezing issues

Hi

We have over 50 WNDAP360 accesspoints. They are on firmware version 3.5.5.0

We still have freezing issues, everything seems to be OK on the front leds, but the acesspoint won't connect/answer to a client. Totaly out of order and users complaying about poor Wi-Fi

a. Are all 50 WNDAP360 access points working fine before?

No, they are randomly freezing/hanging up. We have them on 4 different locations.

b. Are you using a wireless controller?

No!

c. How are the WNDAP360 access points mounted?  Are they mounted on the ceiling or on the side wall?

Most of them on ceiling!

d. Does both 2.4GHz and 5GHz bands have poor wireless connection on every WNDAP360 access point?

It doesn't matter, if one of them hangs up it does not respond on Wi-Fi at all. Usually users tell me that they have  poor Wi-Fi and when I check/scan for Wi-fi I see that this accesspoint is out of order, totaly.

e. What troubleshooting steps have you done so far?

New firmware, factory reset. I have shut down all accesspoints except the one that is freezed for verification. A restart allways help. Why just not have a scheduled restart option on this businnes product it would help us a lot.