A repeater AP must be on the same channel as a gateway AP within wireless range to mesh properly. A repeater should have at least -65 dBm RSSI for best results.
While we recommend using the Auto Channel feature to minimize channel overlap between the gateway APs; networks with many repeaters may benefit from manual channel assignment to ensure the repeaters use the best gateway APs.
To manually assign channels per AP, first make sure that the channel setting under
[Configure > Radio] is set to manual. Then under [Manage > Access Points] select the repeater AP and and select the channel in the Radio box. Assign the repeater AP channel to match that of the target gateway AP to ensure the repeater connects to the desired gateway AP.
For more information about channel use, see: Which channels should I use?