Wow. Trying to follow this thread is difficult. We don't know how to measure voltage. Trying to get a house ready for shtf. Not exactly sure of the model of UPS. And theoretical wiring diagrams and configurations out in the ethers.
Let's try this. Scribble your current wiring and connection map down and slap it up here. I don't care. On a piece of tp, napkin, speeding ticket, mensa application.
I'm very sure there is a viable explanation. The EXACT UPS model you're using. Listen up.
I have an APC UPS with a smart outlet. And a Monster smart power strip. Not saying you have anything remotely similar. But still.
My APC has my desktop PC plugged into the master outlet. All the other crap is either on the slave outlets or on a good power strip on one of the slaves. PC on, monitor, speakers. Everything else comes on too. PC off. Everything shuts off too, the UPS idles down.
And the Monster is the same. My HT receiver is on the master outlet. Everything else.....I think you get it.
So. Cyber Power What?
If you're going to do the shtf thing. You need two things. A bible. And a multimeter. Pretty sure my Simpson 260 will be EMP resistant.
Speaking of. Why haven't you just gotten a good power strip and plugged all of the string of satellite equipment into it?
Consider that a physicians method. If it hurts when you do something specific. Quit! lol.
....coffee