Extend an existing Wi-Fi with an AirPort Time Capsule
I have just a Wi-Fi router at the moment that doesn't have any ethernet port, so I would want to add the Time Capsule to the actual Wi-Fi network just to be able to backup my macs on it, I've tried extend the current Wi-Fi network with the time capsule at the initialisation wizard but though everything seems to be configured fine, after the configuration ends and the Time Capsule reboots I can't see anymore the Time Capsule inside the AirPort Utility app and I can't access that in my network.
Is it possible to add the Time Capsule as a Wi-Fi client and use that just for backups with time machine ?
How? What is the correct procedure ?