Windows 10 FortiClient 6.0.5/9 SSL VPN upload very slow since 2 weeks

[bohm]

Hello,

Since 2 weeks SSL VPN performance on Windows 10 clients using FortiClient 6.0.5 or 6.0.9 is sometimes dramatic. When doing tests on this split tunnel config with a html5 speedtest server in our Datacenter, it shows an upload round 1Mb or even worse. Tests with external servers show an upload as expected with the users ISP speeds like 50Mb or better.

Most of the time disconnecting and connecting again (or several times) solves the problem.

Our Fortigate is a 3700D in HA, servicing around 2000 SSL VPN users simultaneous.

Any idea what is going on? Maybe a Windows 10 update causing problems?

Best regards,

Andre