If you want to tunnel LAN port 4 through VPN via VLAN X3, you need to assign Port 4 to X3 first in the “Network Settings” page. Then, X3 will appear in the WireGuard page. Check X3, uncheck LAN and you’re done. There’s no need to add a WiFi network to X3 unless you want WiFi clients connected to the X3 VLAN also tunneled through the VPN.
