I got a qeustion to you
Does this happen always at any hour?
You said that when the bell rings this pos loose conectivity....if you are with your laptop let say really in the morming when noone is using the POS do you still see the problem?
When you run the command
show ap active ip-addr <ap ip address>
IT will show you the actual noise that it see at that momment... you should try run it many times when you see the issue... to see if you still see non 802.11 interference.
It would be nice if you had an airchecker from fluke.... it can tell you the channel utilization, interference and other good stuff when you do not have the RF licnse for the spectrum analysis...
I saw the output that you gave me and defenely its interference... the
show ap debug radio-stats ip-addr 172.22.140.118 radio 1 advanced | include Busy
Its above 20 which means interference.
Now inotice you ran the commands at different hours.... the uptime of the AP is 21mins... and when you reboot the AP or something like it you wont see the arm history of the AP... it will be wiped....
Did you reboot it? or something happened to the AP?
Collin is right its really hard to troublehshoot it if you dont even have spectrum analyzer to see whats happening...