Installing proxmox and opnsense on MacMini 2012 (Project) - problems

[dev4openid]

Hi all,
I have been trying to get proxmox and OPNSense to work together on a mac mini 2012.  Seeking some advice.

My Virgin Media 1G router is set in bridge mode and it auto sets to 192.168.100.1 (I cannot change this at all)

I can define the virtual bridges etc for the 2 ethernet ports I have connected virbr0 (WAN 192.168.100.1) and virbr1 (LAN - 192.168.100.2).

I read somewhere that I may have to have 3 eth ports (1 for management) and  2 covering WAN and LAN routes for OPNSense.

When I config the ip addresses virbr 0/1 for WAN and LAN routes for OPNSense I cannot get back via port 192.168.100.2 (even though the reboot of Proxmox states 192.168.100.2:8006

Any ideas?
Maybe a no go?

Maybe I can you assign 2x ip addresses to the LAN eth?
I want this to be my virtual router (with DHCP etc) and get rid of my old router