If you choose to do a manual WDS configuration (as opposed to the automatic feature used in the steps above), be sure that all base stations have the same network name. Attempting to give base stations differentiated network names on a WDS network may render the network inoperable. Returning base stations to the network name of the main should return the network to operation.
Click the plus (+) button to scan for your remote base station.
In the sheet that appears, select the remote.
Click update, and pay attention to the messages that go by. Momentarily, you will be prompted to verify settings for the remote base station. In the new or hard reset scenario, the remote's password will be "public", so you should replace that with a more secure password. Because this is automatic configuration, you don't need to change anything else in this dialog.
clipped from: docs.info.apple.com