Another device interfering with HDMI connection. I just bought the Sonos Arc, connecting to my Samsung TV QN65Q70TAGCZB via HDMI ARC/CEC. When my cable box and sonos are connected via HDMI, no sound through Sonos ARC. I can only get sound when I disconnect everything else, to include cable. Everything hooked correctly, tv setup correct. This happens every time the TV is turned off.
Best answer by Ken_Griffiths
Perhaps speak with Samsung Support regarding the HDMI switching issue and losing CEC focus from the HDMI-Arc/eARC port. See this article about some of their TV’s using Auto-HDMI Switching:
Their support desk maybe able to advise how to switch off that feature, otherwise you may have to resort to switching off CEC on your other connected products, or maybe use a CEC-Less Adapter as shown in this link: