We are required to connect the Proxmox Server with a trunk port or a network connection with tagged VLANs. If the trunk port is configured properly, then there should not be any issues configuring the Proxmox server side. Please have a read on this page from Proxmox themselves.
In summary, it is best to configure this via the Proxmox shell interface. In this setup, I choose to use a VLAN-aware Linux bridge. First, identify the network interface connected to the trunk port. In my case, I have the eth0 interface connected to the trunk interface and vmbr0 as the bridge. We have 2 VLANs, VLAN 100 with subnet 192.168.100.0/24 and VLAN 200 with subnet 192.168.200.0/24.
In summary, it is best to configure this via the Proxmox shell interface. In this setup, I choose to use a VLAN-aware Linux bridge. First, identify the network interface connected to the trunk port. In my case, I have the eth0 interface connected to the trunk interface and vmbr0 as the bridge. We have 2 VLANs, VLAN 100 with subnet 192.168.100.0/24 and VLAN 200 with subnet 192.168.200.0/24.