If you mean an IP on the PVE host side, I would not edit the generated `wan1` bridge directly; SDN will overwrite that again. Add it as a subnet/gateway in Datacenter -> SDN -> VNets/Subnets, then Apply SDN and check `ip addr show wan1` plus the generated file under `/etc/network/interfaces.d/`. If the VNet is only meant as L2 transport for guests, the bridge itself normally does not need an address.