As the same thing was happening with both TV’s, I would at least first try a different optical cable, just in case the current one is faulty.

Thank you. I bought a new optical cable but it fits the TV and not Sonos. The original cable is very thin and all the AmAzon alternatives are much thicker. Do you know where I can source an original?

I don’t know, sorry - I just tend to buy cables from Amazon, often from their ‘basic’ range.

I’d also check the source device. If it’s happening on both TVs, it could be whatever is feeding the signal to the TV sets. 

Thanks. I’m using a 4G card currently as I’ve no broadband.

TV speakers work fine, just when I play out through the optical to Sonos that I have problems.