Forticlient 6.0 SSL-VPN Connection No traffic problem

[cuneyt]

Hello,

We have a SSL-VPN connection problem on a specific machine (windows 10). One of our personel connects to SSL-VPN through forticlient (v6.0) to our fortigate 3950B (v5.0). It connets normally as our other personel do until 2 weeks ago. But now when he tries to connect the connection establish but no traffic passing thorugh VPN tunnel. Then he disconnects. After 3-5 connect-disconnect attempts the connection at the end establish regularly and traffic pass thorugh VPN tunnel as expected. 

We also notice that after the first failed attempt we disconnect and shut down all processes from task manager related to forticlient and then run forticlient again and reconnect to SSL-VPN in first attempt without problem. 

I also read the article https://cookbook.fortinet.com/ssl-vpn-troubleshooting/ but can't solve the problem. 

Could anyone help please?