Sorry, I didn't have my controller infront of me at the time. The setting is "Override inform host - Override the Inform Host of your UniFi Network devices with the configured Host for Inform. Enabling this will provision all adopted UniFi Network devices to the configured Host for Inform."
There is an option for you to set the IP under the setting above, for whatever reason when I originally set up the network, I couldn't get anything to adopt without that setting switched on.
When the IP address of the controller changed on my network and I didn't notice, the AP's were pointed to an IP address which no longer was the controller and couldn't be controlled. When I factory re-set them they would start the adoption process and fail because they were re-configured wit the wrong IP. It took me ages to realise what was going on.