Looks like this was available only from 0.7.x onwards. I upgraded to 0.7.3 and got the following error: wpa_supplicant -B -Dwext -ieth1 -c /ubifs/wifi/wpa_supplicant.conf ioctl[SIOCGIWMODE]: Input/output error [404171.320598] unifi0: unifi_siwessid: Join failed, status -5 ioctl[SIOCSIWESSID]: Input/output error