Apologies after the update this morning the docker host running the lemmy frontends (seperate from lemmy itself) was having real issues and took a while to resolve.

All back up and running now :)

Weird issue though - there was an unused container running squid (the forward proxy service) that was causing the system to freeze. The proxmox host node was getting a load average of 600+. Took a while to find it as had to start each container one, wait 2 minutes for it to settle, then try the next.