Hi again Sam,
When I had no sound I tested that all the cables were fully inserted and finger tight, however I still had no sound.
I decided to spring clean ready for a tech visit and untangled my spaghetti junction of cables, unplugging everything including Hub, V6, TV, Switch console, Fire Stick, Computer, X96 box. When I set everything up again the sound worked.
Even if you manage to get the sound back I would still go with the tech visit. especially since VM can't get a signal from the box. Let the tech test everything, possibly resulting in a new box. Also even though your internet is fine, he might find the signal levels aren't as good as they should be and need tweaking.
Dave
The Service you do for others is the rent you pay for your room here on Earth - Muhammad Ali