The system has always worked kinda okay, but recently I started getting a lot of "device not responding" and "no response" errors in the iOS Home app.
It got really bad recently, so I went in search of a solution. I saw one forum poster mention that enabling multicast on his WiFi router helped to solve the problem. I have an Airport Extreme, so I looked up how to enable multicast on it. I found another post that said enabling "IGMP Snooping" would help with multicast and HomeKit.
I gave it a try, and it worked! Turning on IGMP Snooping for an Airport Extreme Is pretty easy. In the Airport Utility go to the "Network" tab and click "Network Options...". Then click "Enable IGMP Snooping" and hit "Save" and "Update". Once your Airport Extreme reboots, your HomeKit devices should start being much more responsive in the Home app.
Here's the steps in pictures if that's more your style:
After doing this, the HomeKit no response errors went away and I enjoyed a much more responsive HomeKit experience.
Photo by Krissia Cruz