Nested VPN tunnels
FortiClient (Windows) does not support parallel, independent VPN connections to different sites. However, FortiClient (Windows) may still establish VPN connection over existing third-party (for example, AT&T Client) VPN connection (nested tunnels).
SSL VPN connectivity issues
Latency or poor network connectivity can affect the FortiClient SSL VPN connection. To further help avoid timeouts, increase the login timeout on the FortiGate to 180 seconds using the following CLI command:
config vpn ssl settings
set login-timeout 180
Microsoft Windows server support
FortiClient (Windows) supports the AV and vulnerability scan features for Microsoft Windows servers.
HP Velocity and Application Firewall
When using an HP computer, a conflict between the HP Velocity application and FortiClient Application Firewall can cause a blue screen of death or network issues. If not using HP Velocity, consider uninstalling it.