Description
Question: How to ensure remote administrative login to the FortiGate via multiple WAN interfaces?
Answer: The default routes associated with each WAN interface must have equal distance.
When there are dual WAN interfaces that are configured to provide failover, you might not be able to connect to the backup WAN interface because the FortiGate may not route traffic (even responses) out of the backup interface.
The FortiGate performs a reverse path lookup to prevent spoofed traffic.
If no entry can be found in the routing table which sends the return traffic out the same interface, then the incoming traffic is dropped.
