Apple TV 4K not auto detecting the Roku TV for volume control?
The Apple TV 4K is similar to the new Roku players in that it autodetects (via HDMI-CEC) what TV/receiver is connected, then sets up its remote to turn that TV on/off and switch to correct input (via CEC), as well as change the volume (usually via IR if CEC not compatible).
I have an Apple TV box hooked up to a TCL Roku TV set (75 C Series), and noticed that the Apple TV could not auto-program its remote to control the Roku TV volume (although Power and Input CEC control works fine automatically).
Luckily I was able to get the Apple TV to manually learn the correct IR codes for TCL volume control:
Settings > Remotes and Devices > Volume Control > Learn New Device...
But Apple's manual learning requires me to point the TV's native IR remote control at the Apple TV box, so that Apple's IR sensor can learn the codes. Well I was using Roku Wi-Fi enhanced remotes (which only fall back to emitting IR when the Wi-Fi Direct pairing connection is temporarily lost). So I had to dig up an IR-only RC280 basic TCL TV remote for Apple to learn from.
P.S. Do all Roku TV brands/models (TCL, Hisense, Sharp, Insignia, RCA, Philips, Hitachi, Element, etc) use the same IR codeset? And do most 3rd party devices have compatibility issues to control the Roku TV volume (either via CEC or by auto-programming the IR codeset)?