All fixed Simon. You were quite right.
It was Vipre. I didn’t know it had turned on its firewall.
The clue was when I tried my Asus Mini PC on my 4K TV, adding Andrus caused Windows Defender to suggest allowing local network access before I could add the Andrus. Once I’d added a tick to allow access, the Andrus was added and worked OK.
Went back to my main PC, switched off Vipre Firewall and everything’s working again.