wlan0: CTRL-EVENT-ASSOC-REJECT

guru

When I came home yesterday afternoon, I could not connect to my Wifi AP, it always said:

Nov 27 16:37:36 ubuntu-phablet wpa_supplicant[846]: wlan0: CTRL-EVENT-ASSOC-REJECT bssid=00:1c:4a:06:17:f5 status_code=1
Nov 27 16:37:43 ubuntu-phablet wpa_supplicant[846]: wlan0: CTRL-EVENT-ASSOC-REJECT bssid=00:1c:4a:06:17:f5 status_code=1
Nov 27 16:40:47 ubuntu-phablet wpa_supplicant[846]: wlan0: CTRL-EVENT-ASSOC-REJECT bssid=00:1c:4a:06:17:f5 status_code=1

Not even a power-cycle of the AP, and not of the BQ E4.5 (OTA-3) helped. Frustrated I went out for dinner and when I returned some hours later, it connected out of the box. No one changed anything in the AP meanwhile and the only thing that changed in my BQ was a connection to some other AP in the restaurant. The AP is a "FRITZ!Box WLAN 3170".

It's a bit tricky to find a list of all status code, it's here in that ~1200 pages doc at page 93: https://www.iith.ac.in/~tbr/teaching/docs/802.11-2007.pdf

update:

To my AP are connecting ~6 laptops (Ubuntu and FreeBSD) and 5 UBphone/UBports devices: OTA-15, OTA-3 and OTA-5;
All connect fine, only the OTA-3 not.
There is no MAC addr blacklisting in the AP. One can configure "allow only known MAC addrs", but this is currently switched of.
The OTA-3 now does not connect at all anymore to my AP, but to all others in my offices and places. I'm clueless what I could do. Are there any know bugs in NetworkManager(...)?
Should I file a bug issue?

update-2:
I found a hint in stackoverflow to higher the debug level of the wpa_supplicant with:

wpa_cli
> log_level
Current level: INFO
> log_level DEBUG
> log_level
Current level: DEBUG

Maybe this gives some more information about the problem.