2 WAN interfaces, 1 gateway

[mmaura]

Hello,

Orange FAI provide a router with 2Gb Fiber internet link, but the switch have 1Gb ports. The router does not support LAG.
I try to add a second interface to my OpnSense to make load balancing at level3, but i don't find the way to use one and same gateway for the 2 wan interfaces.

Can someone help me ?

Thank you.