"AP fails to join controller" - LAP fails to join Wireless LAN controller (WLC) ? Need some help on the query, what could be the issue.
Please refer the below link which can help you .
Please refer to the below link for all kind of information on How to configure the Lightweight AP in order to join the respective WLAN Controller :
https://supportforums.cisco.com/document/8446/how-configure-lightweight-ap-order-join-respective-wlan-controller