Smart AC (2x) and Homekit “not responding” issue.
I have an issue with my 2 (two) Smart ACs. They continuously go to the “not responding state” in Homekit. They are still reachable and usable in the Tado app itself at that moment though.
What works for me consistently as a workaround, is blocking internet access of any ONE, or BOTH Tado Smart ACs in my wifi router. When I do that the “not responding” state does not happen at all in the Homekit app on the Iphone, iPad or Apple TV4K. Of course you cannot use the Tado app after a short while, with internet access blocked for the Smart ACs. But homekit works fine then.
What also works is removing any one of my Smart ACs from power. Then the “not responding state” does not occur for the remaining Smart AC.
Tado helpdesk says it is probably an issue with iOS 15.2. And recommends upgrading to a new beta release, but failed to mention whether this worked for support themselves. After I tried iOS 15.3 beta the issue remained. I am not sure why Tado specifically mentions iOS, the iPad uses iPadOs, the Apple TV 4K uses TvOS, and the Homepod uses HomepodOS.
I have my doubts whether this is iOS related, it seems more like a possible software issue in the Smart ACs that impairs homekit communication when two Smart ACs are connected at the same time to the Tado cloud. Maybe a connection “hangs” sometimes when multiple Tado devices connect to the Tado cloud on a single account, and prevents further network sessions. I see in Discovery DNS-SD app there is no _hap._tcp traffic from the Tado device when it is in “not responding” state.
But I might be wrong, maybe it is a network routing issue or indeed a Homekit issue. But my devices from Eve, Hue and Nanoleaf have no issues at all in Homekit.