Anyone having issues with (WatchGuard) Mobile SSL VPN's?

Hi

We currently have 3 different customers that are having issues with their WatchGuard Mobile VPN Connections.
The VPN works, but after opening and RDP connection over the VPN for example, the connections drops and the VPN reconnects.

We see this in the client log:

Inactivity timeout (--ping-restart), restarting

Nothing special in the logs on the firewall at first sight.

Opened a case with WatchGuard. Maybe a certificate issue somewhere?

Anyone facing the same issue?

Thanks