Technical Tip: Fix the SD-WAN keep failing over to the unstable connection

[AndrewX]

Description	This article describes that the SD-WAN Underlay zone has NBN and 4G connection, the NBN is always good, but the FortiGate keeps failing to 4G which causes the network to be accessible.
Scope	FortiGate OS
Solution	Background: Vocus Internet (wan2) is the main connection, and 4G Cellular Backup (dmz) is secondary. The user temporarily shut down the 4G router to make the devices accessible. To push the SD-WAN configuration from FortiManager to many FortiGate-81Es, however, only this site has an issue      - To change the sequence of underlay zone members, the issue remains. Conclusion: The issue was fixed by rebooting the FortiGate, and then the problem disappeared.