Ubuntu / Linux: WLAN connections fails with "denied authentication (status 17)"

During holidays i was not able to connect my laptop to the WLAN.
The /var/log/syslog showed the following:

Jul 15 13:45:20 pc wpa_supplicant[935]: wlp3s0: SME: Trying to authenticate with 14:9d:09:fe:a4:b3 (SSID='HUAWEI BTV' freq=2437 MHz)
Jul 15 13:45:20 pc kernel: [ 6972.826888] wlp3s0: authenticate with 14:9d:09:fe:a4:b3
Jul 15 13:45:20 pc NetworkManager[797]:   [1531655120.4746] device (wlp3s0): supplicant interface state: disconnected -> authenticating
Jul 15 13:45:20 pc kernel: [ 6972.829942] wlp3s0: send auth to 14:9d:09:fe:a4:b3 (try 1/3)
Jul 15 13:45:20 pc kernel: [ 6972.833433] wlp3s0: 14:9d:09:fe:a4:b3 denied authentication (status 17)
Jul 15 13:45:20 pc wpa_supplicant[935]: wlp3s0: CTRL-EVENT-SSID-TEMP-DISABLED id=0 ssid="HUAWEI BTV" auth_failures=1 duration=10 reason=CONN_FAILED
Jul 15 13:45:20 pc NetworkManager[797]:   [1531655120.5031] device (wlp3s0): supplicant interface state: authenticating -> disconnected
Jul 15 13:45:20 pc org.freedesktop.Notifications[1248]: ** (notify-osd:1448): WARNING **: dnd_is_idle_inhibited(): got error "The name org.gnome.SessionManager was not provided by any .service files"

Hmmm.

STATUS 17

What the hell does this error code tell me?

The explanation was quite easy: The WLAN was provided by a tablet via tethering. And Android limits the number of devices in such a WLAN to 5.
After removing one of the other devices everything worked fine...