EDIT: SOLVED! https://forum.proxmox.com/threads/ceph-cluster-vlan-migration-help-requested.177942/post-824528
So I've been trying to move the ceph network to it's own dedicated vlan11 from where I initially stood this up on vlan1. Every time I add in a monitor IP from vlan11 it doesn't work...
Summary:
When changing the VLAN tag of a VM network interface that has link_down=1,the interface becomes active despite the link_down flag remaining set.
Steps to Reproduce:
1. Bring a net interface down with command: pvesh set /nodes/pve1/qemu/101/config --net0...