It's great to see a new face, welcome to the Community
Thank you for you post and I'm sorry to hear you've had some difficulty signing in. The A01 error helps me identify there's a slight communication issue between the TiVo and the network. After a reboot and still no joy, I'd try to manually connect to the network through this method:-
Help & Settings > Settings > Network > Connect to the Virgin Media Service now.
Let me know how it goes after trying to sign into again, if this issue is still happening