Wan-Link Manager shows wan down, but in reality its up

I feel like I had a similar issue where the gateway appeared to always be down when it obviously wasn't. (Didn't have any indication of loss of packets dropped, though.) I can't remember the exact solution but it was something like changing a setting on the gateway, changing it back, then saving and suddenly it was up. Like a corruption in a setting somewhere. Sorry I can't remember the details.

I feel like I had a similar issue where the gateway appeared to always be down when it obviously wasn't. (Didn't have any indication of loss of packets dropped, though.) I can't remember the exact solution but it was something like changing a setting on the gateway, changing it back, then saving and suddenly it was up. Like a corruption in a setting somewhere. Sorry I can't remember the details.

I've had the same, it was a backend database problem - the solution offered was to delete and recreate the interface but as the site only has the one link and is remote it's not going to happen for a while (and doesn't cause any problems in this instance).

My Solution was to hit SAVE again under Interface configuration.

Yes, i was avoiding it since it would also delete all the rules associated with it, but ultimately i have deleted it and created the WAN interface again. Now the issue is resolved.

hitting the save button also worked for me to get the interface green again

So like others have said, deleting and recreating might not be necessary, just saving the interface configuration without changes can fix some issues. With at least three of us having it work in the past. I think that should be noted in the accepted answer so people don't have to go through deleting and recreating and the side effects of that.

Also, you say you lose associated rules, but which rules are those and are they port-oriented rather than zone-oriented? That's one of the benefits of zones: you can change what ports are in what zones without affecting Firewall rules.

I had actually tried saving it but that did not yield any result.

And yes, the rules were associated with ports instead of Zones.