How to resolve failed to establish the VPN connection in Windows 11

While connecting the FortiClient the below-mentioned error can appear.

This error happens because of the TLS mismatch.

Step 1: Go to Internet explorer -> Settings -> Internet options -> Advanced, scroll down and check the TLS version.

From the above Image only TLS 1.2 is selected on client end while the FortiGate does not support TLS 1.2

Step 2: Verify the TLS settings configured on FortiGate end as well as the TLS settings on the client end.

Step 3: In this case, change the settings on client machine end. Now, select the TLS 1.1 and TLS 1.0 on client machine end.

As soon as settings are changed connect the FortiClient is possible.