Happy New Year; The hack I did to the HDMI cable for my DVR stopped working this morning, so we couldn’t change the volume (Error from Sony TV: The TV Volume is Fixed).
When we upgraded to the BrightHouse (Spectrum) Voyager Whole Home DVR (now discontinued) our Sony TV stopped changing the volume of our surround sound system and the Apple TV wouldn’t switch inputs.
Did a little Google searching 1 and discovered this is a known problem with the Arris DCX3600-M. The only solution is to destroy pin 13 in the HDMI cable which is what carries HDMI-CEC. A tiny screw driver did the trick to move the contact out of the way. Cheaper than buying a HDMI-CEC disabler switch
Hope this helps.