Currently, the firmware got bugs, revoking your access to n preferred wireless connections, timing out and asking for authentication afterwards (which is totally misleading btw!).
In order to regain access based on the basic channel without n technology, put the n support into disabled state, and re-add the driver.
sudo rmmod iwlwifi sudo modprobe iwlwifi 11n_disable=1 echo "options iwlwifi 11n_disable=1" | sudo tee -a /etc/modprobe.d/disable-n.conf