Multiple WAN links using a managed switch on DMZ port of the modem

[jarif]

I'm trying to create 4 WAN ports to my OPNsense using a HP OfficeConnect switch and a VDSL2 modem (DMZ port).

The idea is that I could get 4 different bridged connections which I might be able to NAT 1-to-1 some some internal hosts. The modem has only 1 DMZ port, but my ISP offers 5 public IPs, which would be 1 for router and 4 for DMZ in this scheme.

I have 5 ethernet ports in my server, connected as this:

1. OPNsense connected to modem - routing mode VLAN 1
2. switch connected to - modem - VLANs 2-5 tagged
3. OPNsense connected to switch - VLAN 2
4. OPNsense connected to switch - VLAN 3
5. OPNsense connected to switch - VLAN 4
6. OPNsense connected to switch - VLAN 5

Without the separate VLAN's OPNsense crashes miserably when it tries to initialize 2nd WAN-port. Apparently does not like multiple WAN ports in same subnet.

I have configured the VLAN numbers to both the OPNsense and the switch.

Is this totally wrong approache? At least I can not get it up and running...