Hi,
I'm currently testing SDN with 7.4. I configure a VLAN zone as per https://pve.proxmox.com/pve-docs-7/chapter-pvesdn.html and https://pve.proxmox.com/wiki/Software-Defined_Network#pvesdn_setup_examples.
This is a very basic setup with a Zone "cluster1" (no DNS, no DHCP for now) and a VNet...