Comment 89 for bug 548992

I had the same symptoms (deauthenticating from ... by local choice (reason=3)) and have managed to find a solution on a Thinkpad x61s using wlagn driver.

I had the exact same problem on Ubuntu 10.04 after an update, and then again after wasting hours going to 10.10.

Updating wpasupplicant to latest ppas didn't help (I have wpasupplicant_0.7.2-0ubuntu1~ind1+r2001+201009072031_amd64.deb and wpasupplicant_0.7.3-0ubuntu1_amd64.deb but seem to be running wpasupplicant_0.6.10-2_amd64.deb successfully).

Updating network-manager to latest ppas didn't help (I have network-manager_0.8-0ubuntu3.10.04.0~mtrudel~nm1_amd64.deb
network-manager_0.8.3+git.20101219t181118.e919218-0ubuntu1_amd64.deb but seem to be running network-manager_0.8.1+git.20100810t184654.ab580f4-0ubuntu2_amd64.deb successfully).

Using linux-image-2.6.37-11-generic from natty didn't help.

Disabling ipv6 didn't help.

Replacing dhcp3-client with an alternative didn't help.

Adding options iwlagn 11n_disable=1 11n_disable50=1 didn't help.

My problem was actually obvious, after running wicd and noticing I had two versions of my SID on the same channel. I did actually have a repeater at some stage, but had since removed it (and I'd forgotten this fact; it's been nearly a year since I touched my wireless setup).

I'd moved some router gear and somehow the repeater was now activated again (when it shouldn't have been), so now the "reason=3" makes sense - my thinkpad was roaming to the "new" AP, and then failing to get an IP address (or talk to the router).

I simply switched off the mis-configured, superfluous AP and now everything works properly after a couple of hours.