since some weeks we are getting connection problems using FortiClient SSLVPN on Windows 11 computers. Once the issue appears on a client there is no workaround applicable, simply stops working forever, not all the W11 PCs are affected (for now).
The client stops injecting the routes to the system, only the firewall public IP related route is added.
We believe the issue comes from the Windows endpoint and not from the Fortigate configuration.
Unfortunately there is no way for us to determine if the issue is related a windows update package.
We tried several release and combinations of the FortiClient SSLVPN (FortiSSLVPNclient.exe) and of the FortiClient VPN on several Fortigates without success. No manual or tool based removal or client reinstall solved the issue.
We got it to work on 1 computer, but not all. We do not even understand why it would work. What we did is that we exchanged the hostname with the ip address of the VPN server. After doing so, we can logon. It asks us to accept a certificate, but that is easily fixed by importing it (user certificate).
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