Thank you for using Apple Support Communities. Based on what you stated, it seems like the Apple TV (3rd generation) is not working remotely with HomeKit anymore. If it is not working remotely, there could be a few things causing this. Have you added an Apple TV (4th generation) to be used with HomeKit? I would recommend you read this article and use it to help troubleshoot the issue.
Automate and remotely access your HomeKit accessories
- Make sure that your Apple TV or iPad is:
- Connected to the Internet and on the same Wi-Fi network as your other iOS devices during set up
- Updated with the latest version of tvOS or iOS
- Signed in to iCloud with the same Apple ID with two-factor authentication enabled
- Make sure that you can control your accessories in the Home app on your iOS device. Open the Home app and turn on a light or change the temperature.
- Make sure that your device is set up as a home hub:
- On your Apple TV, go to Settings > Accounts > iCloud and make sure that your Apple TV shows HomeKit as Connected. If you don’t see HomeKit, then your Apple TV isn't connected as a home hub.
- On your iPad, go to Settings > Home and make sure that Use this iPad as a Home Hub is turned on.
- Restart your Apple TV, iPad, and iPhone.
- Wait a few minutes. If you still need help, sign out of iCloud on your Apple TV, then sign back in. Go to Settings > Accounts > iCloud.
If you have an Apple TV (3rd generation)*, you can control your HomeKit accessories in the Home app while you’re away from your home. To change user permissions, create automations, or stream HomeKit-enabled cameras remotely, you need an Apple TV (4th generation). If you add an Apple TV (4th generation) to a home that has an Apple TV (3rd generation) set up, the Apple TV (3rd generation) will stop being used for HomeKit remote access.
Cheers.