Useful links & discussion

PVE docs - Cluster Manager
Made mistake in corosync.conf; now cannot edit
Create Proxmox Cluster (over a private network) using Tailscale
Remove a Cluster Node (There IS some dumb in these instructions...)
- If you still see the removed node in the GUI afterwards...
- You need to remove the whole directory /etc/pve/nodes/<nodename>

Unapproved Things

(AKA... How to do things the developers say can't be done to Proxmox Clusters.)