If your device has become unresponsive to HomeKit it has either lost its WiFi connection or its HomeKit connection. This article will help restore the connection and keep it.
Are you using mobile data?
If your device is unresponsive but you're trying to connect to it using a mobile data connection, you might need to setup Remote Access.
Remote Access requires either a generation 4+ Apple TV, iPad or HomePod. For help setting it up please refer to Apple's website: https://support.apple.com/bg-bg/HT207057
Can't setup Remote Access? You can use the WIFIPLUG app instead!
What are you using as your HomeKit hub?
Apple say that you can use an iPad as a HomeKit hub but this may not be your best option for reliability. From customer feedback and internal testing we have found that using an Apple TV (that is set to never sleep) provides better HomeKit reliability than an iPad when it comes to HomeKit hubs.
Is it also unavailable within the WIFIPLUG app?
Login to your WIFIPLUG account and check the status of your device there. If it is also unavailable, it is likely that the device has lost its physical WiFi connection. Please refer to this article instead for help remedying this problem.
How often does it happen?
WiFi disconnections are unavoidable. Unfortunately, it's a limitation with the service that affects every connected device at one point or another. If your device has lost its connection, start by removing it from the mains for 10 seconds then reconnecting it. By powering the device down then back up, you are forcing it to re-establish its connection. Your device should become available within a minute of powering it back up.
Is everything unresponsive?
If when you open the Home app everything appears to be unavailable or unresponsive, start by checking that your network is online. If everything from a network point of view seems OK, you might need to start resetting your devices one-by-one.
It might be iOS
To begin with, make sure that all of your iOS devices that have access to your device via HomeKit are up to date.
If the issue persists you might need to reset your HomeKit configuration. WARNING: This will wipe your entire HomeKit configuration so all devices and automations will need to be setup again. It should however, fix any background errors with the current configuration.
To reset your HomeKit configuration open Home > Navigation icon (top left) > Remove Home.
Still having trouble? Time to contact Apple
When it comes to HomeKit, everything is provided by Apple. If you're still having trouble after trying the above please contact Apple for further support.