Link monitor: interface wan2 was turned down

[simonl]

Hi all,

Lately I've been getting an alert from FortiCloud about our Fortigate router:

Link monitor: interface wan2 was turned down

Device: FG100E########## Severity: HIGH

Handler: Interface Down

The interface looks like it's up whenever I check. I'm also run a ping to detect if it goes down at all. It doesn't and the warning still trips. Some details about our setup:

- wan2 is part of the SD-WAN object with wan1.

- we don't have any performance SLAs configured.

- running firmware 6.02.

What other steps can I try to troubleshoot?