- traffic flow towards a WAN port is directed according to routes. See Network > Routes > Static. In case of multiple WAN ports, you would set up 2 default routes ('0.0.0.0/0') with the same distance. This is then called ECMP and the FGT will load-balance sessions (not: bandwidth!) among those ports.
- to divert traffic from a static route towards another port, use Policy Routing. PR is working just like routes, but additionally to the destination you can base the routing decision on source address, source port, destination port (not on: application, schedule, UTM filter,...).
Policy routes may be cumbersome sometimes as they don't show up in the routing table. They are checked before ordinary routing takes place.
Keywords: dual-WAN, ECMP, LLB, virtual WAN port; Policy based routing, policy routing.
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