Your TV and Arc are communicating through CEC controls.  This is how your TV knows there is an Arc present and that it should send audio over HDMI-ARC.  With Samsung, other devices connected to the TV that also use CEC controls seem to ‘confuse’ the TV and stop it from sending audio.   You can verify this by turning off CEC in your other connected devices, or unplugging them if not possible.  You can get ‘CEC less HDMI adapters’ to block the CEC commands for devices that are causing issues and don’t allow you to turn off CEC through settings.

Hi 

    My Sonos ARC has recently started losing connection to my Samsung tv every time I turn off the tv, to reconnect i need to unplug the tv and replug then the ARC finds the connection again.

Is there an update or fix I can use to correct this problem  

I have run a diagnostic which is 1971928014.

Thanks Peter 

I have a new Sonos ARC connected to a Samsung TV via the hdmi ARC port and each time I turn the TV off for a few hours it looses its connectivity.  The TV reverts back to the TV speakers and the only way to get it to recognize the sound bar is to reboot the system by powering down and setting up again.  Then it will work.  
 
I have spoken to Sonos support.  Diagnostic # 2132805758.      Case #xxxxxxxx

Just wanted to reach back one more time before I return the soundbar.   Great product otherwise.  Thank you!

Mod Edit - removed case number