Volume and mute doesn’t work on remote.

Volume and mute don’t work on remote

Do you have the Siri Remote (2nd generation)? Identify your Apple TV remote - Apple Support

Please describe your audio setup. Do you use the TV’s built-in speakers, or something else?

Try restarting the remote, as described on: If your Apple TV remote isn't working - Apple Support

Apple TV HD, tvOS 14

Users are advised to keep their devices up-to-date for best support, features, bug fixes, security, performance, and stability. We’re on tvOS 16 now. Update your Apple TV - Apple Support