After applying the last Big Sur update for MacOS (11.3.1), FortiClient 126.96.36.1995 and 7.0.0.0022 are having problems connecting successfully. After some attempts my SSL VPN connects again, but the IPsec connection consistently refuses and says that my pre-shared key is incorrect. However, this same pre-shared key continues to work successfully with the MacOS built-in IPsec VPN connection, so it clearly points to a problem with FortiClient.
After some further troubleshooting, I found out that our pre-shared key doesn't work anymore in combination with FortiClient on MacOS 11.3.1. This key is rather complex and long, but it has always worked well, until now. Having tried with a shorter and less complex pre-shared key I can confirm that the IPsec connection started working again.
However, as the macOS built-in VPN still doesn't have any issues with this long and complex pre-shared key, it has to be a limitation between macOS 11.3.1 and FortiClient.
Is anyone else experiencing problems similar to this?
Thanks, kind regards,