Why the fuck they don’t just have a button to do this like VMware I don’t know. Probably a German thing. Either way there is no GUI way to enable a maintenance mode, BUT there is a sneaky and useable way from the command line. To disable “start at boot” without manually changing the VMs and LXCs use:
systemctl mask pve-guests.serviceThis only stops the service that automatically starts guests. Once you’re done:
systemctl unmask pve-guests.serviceFeel free to open a bug with the Proxmox team as this should be easier.