I have a Samsung TV - model number UE 50 MU6120 - I’ve had the beam connected to this for a number of years. It’s recently lost connection between the TV and the speaker - I’ve tried resetting the unit and running through the set up process again

I get one of three errors I) “ARC connection not working” or ii ) “devices on the network are interfering with the ARC connection” or iii) “switch on ARC mode”

when I try to set the expert settings - there’s nothing available saying ‘ARC’ or ‘CEC’ mode. The best I have is ‘HDMI input audio format’ saying whether you want to have it as ‘PCM’ or ‘bitstream’. Neither options work

I’ve disconnected all other devices connected to the TV (removed the Roku stick, unplugged the DVD player) and removed all external device connections from the TV. Important to note that the WiFi connection is via a WiFi extender. This was working previously. The TV and Sonos system are both connected to the WiFi extender network. I’ve yet to try going into the admin settings of the WiFi network to see what devices are connected and to remove but I’m struggling to see what that would do
 

I’ve done the basic checks - tested that no one’s moved the HDMI port connection, I can see through the TV external input display channel that the HDMI cable is connecting the unit to the TV (it has the black-and-white patterned Sonos background showing), checked for software updates etc

 any help appreciated!