: If you are experiencing issues, it is often best to completely uninstall previous versions before installing 6.4.3.
: During setup, you may be prompted to "Allow" FortiTray to load in the Network Extensions settings to ensure the VPN functions correctly.
: The most direct way to find specific legacy versions like 6.4.3 is via the Fortinet Support Download Portal . After logging in, navigate to Support > Firmware Download , select FortiClient as the product, and browse the v6.00 > 6.4 > 6.4.3 directory.