Same Gateway, Multiple WAN Configuration Question

[korea153]

I am planning to set up an OPNsense system with 4 WAN ports and 4 LAN ports. The 4 WAN gateways are all the same but have different IPs. I intend to assign the 4 WAN IPs to the 4 LANs individually. I know that FreeBSD does not support different WANs with the same gateway, so is it possible to configure it this way? Or would it be better to set up OPNsense on 4 virtual machines using Proxmox, Hyper-V, etc.?

[Maurice]

Are these actually four different gateways which happen to have the same IP address or is it just a single gateway? For the latter, you won't need four WAN interfaces. You can add all IP addresses to a single interface by using IP aliases instead.

Cheers
Maurice

[korea153]

It's the latter. Can you elaborate on how I should use the ip alias?

[Maurice]

Configure the WAN interface with the first IP address, add the other three as virtual IPs (IP aliases). Set outbound NAT to manual and create four rules, each mapping one LAN subnet to one WAN address.