I’ve done some research and from what I can tell: (1) there was a very recent Kasa API change that that broke HA but only impacted UK users, (2) there’s been a long standing issue in which Kasa devices go unavailable given enough time.
I think I’m fighting #2 as reloading the integration works for a few days. I saw mention of a rewritten Kasa library from back in Sept. I think the PR got accepted. How can I tell if I’m running the latest Kasa integration and is there confirmation that this has fixed the issue? I also saw a comment that assigning them a static IP address helps, but it wasn’t clear if that’s confirmed.
Unfortunately, if I can’t get this resolved. I’m going to have give up on HA for the time being. I have too many Kasa devices and the reliability makes this a non-starter for the family. I’m not happy with Kasa (lack of openess as well as back peddling on HomeKit support) overall so long term I’ll be moving away from them picking up other options as I see good deals pop-up.