Routing WAN traffic... via the LAN

[rocketraman]

My WAN link is down due to a fibre cut.

One of my LAN boxes (a Linux box) is acting as a temporary gateway to the WAN via a WiFi connection and mobile hotspot.

What is the best way to configure OPNSense to route WAN traffic to this particular Linux box, which can forward the traffic to the WIFI interface?

I believe it'll be a gateway configuration, but some specific advice on how to do it would be great. I already lost local connectivity once to opnsense with a misconfiguration (thanks for the ability to restore!).

[bartjsmit]

Add a VLAN for the backup WAN connection to the Linux box using the LAN interface as a parent. Use an access port on the VLAN for the Linux box or trunk it if you have other services on it.

Add the gateway as normal to OPNsense

I use a 4G router for backup.

Bart...