The AP650 is a "DEPENDENT" AP. It needs the controller to push out the configuration. If the AP is on the same broadcast domain, there will be no issue. If the AP is on a different subnet then the controller, the "CONTROLLER HOST" variable is needed. On a power fail/ reboot, all configuration data is lost on the AP650 and if they are on a different subnet, they will not be able to locate the Controller. If this is the case, the CONTROLLER HOST variable can be set using DHCP Option 191