I mentioned this in another post, indirectly ... but yes! When I was trying to use HomeKit to automate everything, I could *never* really prevent random devices from "greying out" in the "Home" app on my iPhone and becoming unresponsive. Usually, just ignoring it for a while and checking back later would show them back up and running in the app.They suck as HomeKit products though. Siri takes ages to set scenes since iOS 15. A lot of things just fail too, without explanation. I’m growing very tired of HomeKit not working properly and regretting investing heavily in the system.
I know there were a lot of reasons this could happen (including the Netgear Orbi routers having buggy firmware for a while which would block HomeKit communications). But I worked through all sorts of issues with that stuff for a good year's time, and concluded the reliability just wasn't there. (EG. If I shared the Home control with my wife's phone and iCloud login, her phone wouldn't consistently mirror all of the devices I'd see in mine.) HomeKit really didn't play well with any devices that had their own IP addresses on your local network, obtained via DHCP, if those were subject to change, too. Belkin Wemo plugs and switches worked that way, and I had to "pin" fixed IP addresses for each based on its MAC address in my router to get them to work better.