It’ll be an HDMI-CEC problem. If there’s a setting on the satellite box to disable CEC (it could be called ‘device control’ or some such) then try that. Otherwise there are ‘CEC-less’ adapters available from Amazon to insert into the HDMI connection. 

I would first try a different HDMI cable and then go onto check any other devices connected to the TV’s other HDMI ports, to see if they are stealing the CEC focus. The easiest way to do that is to disconnect each device for a time and see if the issue goes away. If a device is identified as causing the problem, then simply switch off CEC on that one device only, or insert a CEC-Less adapter to stop it intermittently taking control.

(edit: @ratty beat me to it). 

Also make sure that TV Autoplay is enabled under the Arc’s settings in the Sonos app.

Thanks to each of you. I will try out your suggestions in the morning and update you.

Many thanks. JoeKLSA

Hi, I have just checked the CEC setting and it is not enabled. Just tried a different HDMI cable. Now to wait and see if this random error reoccurs.

Thanks everyone 

The latest! The system has been working well since my last post. 2 hours ago we watched the news and then switched off the TV. Switched it back on just a few minutes ago and......no sound. Switched all off at mains and when I switched back on, guess what? It worked. So back to square one!

Any other ideas.

Thanks,

Joe

Exact same issue for me, random sound error from TV after switching off or using my Beam in Wifi for music streaming.

Desconnecting and connecting HDMi again can solve the issue sometimes but not always.

I try to control and force TV choice with the app but no sound from the Beam…

Someone already understood the problem ?

One thing I’d double check, beyond the answer given above, is if the TV has any software updates. Once I’ve checked that, I’d reboot the TV by unplugging it from the wall for two minutes.