NetworkManager[920]: Connection disconnected (reason -4)

Using 14.04 on a ThinkPad X1 Carbon, a WiFi which works fine on other laptops regularly disconnects "by itself", and only comes back on after a forced Disable/re-Enable WiFi. In /var/log/syslog I've, among other things, noticed this:

NetworkManager[920]: <info> (wlan0): supplicant interface state: authenticating -> associating NetworkManager[920]: <info> (wlan0): supplicant interface state: associating -> associated NetworkManager[920]: <info> (wlan0): supplicant interface state: associated -> 4-way handshake wpa_supplicant[1343]: wlan0: WPA: Key negotiation completed with a4:52:6f:8e:ff:01 [PTK=CCMP GTK=TKIP] wpa_supplicant[1343]: wlan0: CTRL-EVENT-CONNECTED - Connection to a4:52:6f:8e:ff:01 completed [id=0 id_str=] NetworkManager[920]: <info> (wlan0): supplicant interface state: 4-way handshake -> completed wpa_supplicant[1343]: wlan0: CTRL-EVENT-DISCONNECTED bssid=a4:52:6f:8e:ff:01 reason=4 locally_generated=1 NetworkManager[920]: <warn> Connection disconnected (reason -4) 

What does mean, and (more importantly ;-) how can this be fixed?

I'd be happy to update the Q with more information if you respond to the Q with what's needed.

1 Answer

I found this:

It may be bluetooth interference with a bluetooth device on the laptop itself... try to change wifi channel to 13 or disable bluetooth on the laptop when not used.

UPDATE: changing wifi channel solved my stability problem, i had the very same error message (reason -4).