Apple TV remote and Bose Lifestyle sound

When Apple TV cannot use HDMI CEC for Volume Up, Down and Mute it will use IR instead and you can have Apple TV learn IR codes from your AV Receiver remote or Soundbar remote. See below.

1. Go to Settings App > Remotes and Devices > Volume Control.

2. Select Learn New Device…

3. Follow the onscreen steps to program your Siri Remote to control volume for your Soundbar. Make sure you use the Soundbar remote (not Siri remote) for the onscreen Learning.

Make sure under Settings > Remotes and Devices > Volume Control, the device you just learned is selected.

Volume + - or Mute not working - IR Trouble Shooting for Siri Remote

Source: New Apple Siri Remote 2021 Owner’s Thread + FAQs + User 

Hi jterrie, thanks for posting in Apple Support Communities. We understand that you aren't able to control the sound on your Bose Lifestyle system with your new Apple TV remote, as you were able to with your older Apple TV. You also mentioned that the older Apple TV was placed in a spare room, by any chance, is that Apple TV set up and in use in that spare room? If so, let's try this: Unplug that Apple TV from its power source and ensure that its remote is out of range of your new Apple TV. Once done, redo the set up of your new Apple TV remote with your Bose Lifestyle system.

If that doesn't help, we recommend giving the steps within the following resource a try: If you can't control your TV or receiver with your Apple TV Remote - Apple Support

Please keep the community posted on the results.

Cheers!

You also mentioned that the older Apple TV was placed in a spare room, by any chance, is that Apple TV set up and in use in that spare room? If so, let's try this: Unplug that Apple TV from its power source and ensure that its remote is out of range of your new Apple TV.

When you pair a Siri remote, it automatically unpairs the previous one. Only one Siri remote can be paired at a time to a specific Apple TV. Please post if unplugging works, I will be surprised.

Want to make sure I understand so I can better help you.

You are stuck on this Screen on Volume +, progress bar not moving even if you press Vol + on Bose remote pointing at front side of Apple TV box?

That is great news that you got it working even though Apple TV 4k (2nd gen) can learn IR volume from Bose Lifestyle.

Very smart that you used the Apple TV built in IR codes for Bose Lifestyle.