Not sure if this is helpful but I’ve noticed this behavior.
Sometimes I’ll get a no response from some of my homekit devices for whatever reason. Like maybe my internet went down or I had a brief power failure so my WiFi basestations are rebooting or maybe just aliens messing with us humans.
But all my homekit devices will come back online within a short time except rachio. Rachio doesn’t seem able to recover from a brief outage.