FortiExtender shows as offline

Hi,

I've got FortiExtender connected to a switch that is connected to the Fortigate.

The FortiExtender works great and is a part of the sdwan (checked and working).

In the Extender menu it shows as online but in the Topology and in the Dashboard the Extender shows as Red (Offline)

Reading simmilar past post:

1. I've got NTP set on that port and the Extender syncs clock from it

2. I got CAPWAP enabled on the port and the Extender mode is CAPWAP.

what can make it look offline?

Additional info: FortiExtender is connected on its own vlan and Security Fabric and ping are marked as allowed.

Thanks,

Lior.