FortiGate WAN Status Check permantly goes down and up

Hello,

we've had a  problem lately that all VPN tunnels have been disconnected.

In FortiAnalyzer in the Event Logs for System I could see, that at those times the Static Route for the WAN Status Check has changed.

Message:

Static Route is removed. Route xxxx -> xxxx ping-down.

and then 1 minute later:

Static Route is added. Route xxxx -> xxxx ping-up

I assume that this is/was a provider problem.

Do you see the same or maybe the firewall can be guilty.

If anyone has any suggestions for me, please come here. Thanks for every advice.

We have a FortiGate 500D with FortiOS 5.4.6 installed.

A picture of the Message is attached.

Kind regards

Tobias