@olivierlambert I watched this video by Tom @ Lawrence Systems. Now I understand everything.

https://youtu.be/1tJZAc-A4kU

I hope this video helps everyone else confused about backup.

@borzel Indeed, the command

"xe vm-cd-eject --multiple" worked! All VMs now correctly auto boot on reboot/startup!

@chon It's Jun 3, 2023. After three years, I'm going to finally do the migration to a new Dell server hardware. I'll update this thread for those who are interested. thanks.

@Danp they are stored in a FreeNAS physical server connected to another physical hardware with xcp-ng. The link via iScsi.

Thanks. I guessed that I needed to put the full path on FreeNAS as there is not masking when expose as NSF by FreeNAS. So I put the full path as "/mnt/MybooksVolume/VM_ISOs" and that seems to have fixed the problem.