What could cause sudden total failure and then back to normal a couple weeks later?
Background
I set up what I believe to be a common X10 system in our home perhaps 10-15 years ago... back to the "Radio Shack period." It controls lighting in family room, living room, and yard lights. It's been pretty stable, although 5-6 years ago I had some problem. On the advice of JV Digital Engineering had a XPCR Coupler Repeater Amplifier installed. Also bought his XTMB Signal meter.
Now roll through several years until Thanksgiving this year (2022). Suddenly nothing worked. No response to button pushes, timers set up with app, absolutely nothing.
So over the last couple weeks I've been replacing modules, testing signal strength, moving the transceiver, etc. Nothing helped.
Then this morning my wife mentioned the living room lamp went on when she pressed the Family Room button, and off if she pressed the off button. I checked and found I had the Appliance Module with FR settings so I traded the two Modules. Everything worked using the wall pad controllers too.
BTW, this was with a newly purchased CM15A mounted in the laundry room where it has been for years. My guess is the old one will also work.
Keeping in mind I have changed nothing since yesterday, my guess is the whole thing was because something happened in the power lines, main electrical panel, or the
XPCR Coupler Repeater Amplifier. Or, perhaps some neighbor set his house code to L, like mine, and was having parallel experiences. He caved in first and changes his to M?
Or, what else could be responsible for this bizarre behavior?