AirPort Extreme Time Capsule will not restore to factory settings
I've got an Airport Time Capsule that I was using as a router in addition to being a TimeCapsule for my Mac. I just replaced the router with a mesh network setup, but I'm hoping to still use the TC to backup the Mac. I've reset it several times following instructions, but since I don't want the TC to create a new network, I select "Add to existing network". At that point it simply jumps back to the "This Airport Time Capsule will create a new network" dialogue.
It seems like the reset hasn't actually worked (well, more accurately, the many factory resets); shouldn't it be asking me a new set of questions? I seem to remember a different set of options when I set it up the first time.
I can't even use the menus at the top of the AirPort Utility on the Mac, since the TC never registers on the network for me to select it. Is there any other way to force the reset to work better?
At one time I had a nice little network of the TC/Router and several AirPort Expresses. The Expresses have all been happy to reset and extend the new network.
Does anyone have any advice? Is this AirPort really done for? Kinda sad to lose the TimeMachine capability.
(I guess the Airport is so old, the forum selector chose HomePod for me because nothing else was available)