Orbi RBR/RBS50 not syncing and connected devices not showing

A manual firmware update is not the solution, because the Orbi is already on the most recent release.

What steps have already been tried:

Power them both off.

Power up the Orbi and wait until it comes up, which takes a LOT longer than I expect it to.

Power up the satellite.

Does that have an effect?

The "last resort" is to perform a "Factory Reset" on the system, based on the theory that "something got corrupted" in operating memory by the power outage and that "starting fresh" will create all the internals correctly.  Depending on how much was done to customize the Orbi (device assignments, defining device names, customizing DNS entries, setting up DDNS & VPN, etc. etc.) this can be a serious effort.

This is usually done in two ways: (1) before the reset, save a copy of the configuration file to an external computer.  This is on the Orbi web interface, Administration, Backukp Settings.  After the reset, there will be a chance to "restore previous settings".  So, way 1 is not painful at all.  (2) However, if way 1 fails to solve the problem, The second method is to say, "Nope.  I am setting this up manually", and enter every blasted item by hand.  My tactic is to NOT set the Orbi WiFi name until the very last.  With a different name, no devices will connect to the Orbi and mess up my configuration process.  After all entries are done, I change the name, the Orbi restarts, and it's a wild scramble as all the devices connect.  In order to do this, I make screen captures of every single page of the Orbi web interface and save them in a Word file.

The Factory Reset process is explained in this video: https://www.youtube.com/watch?v=cMw4ePACgc4