Failed To Established A VPN connection Using FortiClient When I used Mobile Hotspot

Hi, 

The connection works really well using my home broadband I moved out recently to a place where I have no access to the broad band at the moment  and I am waiting for my broadband to setup.

The problem is now I am using Mobile Hotspots to connect to VPN using forticlient and I am recieving the error shown in the picture below. I hope you guys help.