The vastly improved Siri Remote that ships with the fourth-generation Apple TV includes dedicated volume buttons, which can be programmed to control volume levels on TVs and receivers, even via legacy infrared line-of-sight.
Some more modern HDTVs and receivers allow connected devices to control power and volume via the HDMI cable. Right out of the box, the new Apple TV is configured to support devices compatible with what is known as HDMI-CEC.
For older devices that don't support HDMI-CEC, users can program the Siri Remote to mimic their legacy remote and allow for volume control.
This can be set up by opening the tvOS Settings app, choosing Remotes and Devices and selecting Volume Control. From here, select Learn New Device...
Users can then grab their traditional TV or receiver remote control and point it at the Apple TV, and are instructed to hold the volume up and then volume down buttons. The infrared receiver built into the fourth-generation Apple TV will learn the remote commands for volume up and volume down.
After sending the proper commands, the Apple TV will ask the user to name their new remote for easy identification later.
Once the volume controls are programmed, the plus and minus buttons on the bottom right of the Siri Remote will now successfully adjust sound on a legacy TV or receiver, thanks to the infrared transmitter positioned on the front of the Apple TV remote.
For those with HDMI-CEC compatible TVs and receivers, control settings can also be customized through the "Remotes and Devices" menu under "Home Theater Control." There, users can enable or disable volume control and turning on and off of the TV when the Apple TV is put to sleep. If the connected accessory is not HDMI-CEC compatible, "Turn On Your TV with Your Remote" will be greyed out.