Two problems.

[RLynwood]

One down, one to go.
"2. Using KDE Connect to sync this new tower 24.04 with my laptop's 24.04, I'm told that "All paired devices are unavailable." How do I get their availability so as to get the laptop paired and communicating with the tower?"

[z_mikowski]

Kubuntu Focus Firefox advice covers installing it so it is upgrades with the rest of the system. There's are other bits of advice that may be useful too.

[RLynwood]

What has Focus' Firefox advice got to do with syncing KDE Connect between my two computers?
Further, though I'm glad to learn of Kubuntu Focus, it's a computer, not a downloadable OS, so it's irrelevant to me.