Unfortunately Mac users typically report a higher number of problems with Forticlient than Windows users, it's generally not a problem with the VPN service itself but a problem with MacOS and Forticlient not playing nicely together.
If your VPN connection was previously working fine and you get a Connection Error out of the blue there's a good chance you'll be able to resolve the issue by restarting your computer. If a restart takes too long or for whatever reason you'd prefer not to restart your computer the problem can also frequently be resolved by shutting down and restarting Forticlient.
- Locate Forticlient in your taskbar near the clock in the upper right. The icon should look like a shield.
- Click on the shield, you should see a menu listing all your Forticlient VPN connections, below that list click the option to Shutdown Forticlient
- Shortly after you click Shutdown Forticlient the shield icon should disappear from your taskbar. If the icon doesn't disappear after a minute or two it may need to be manually terminated using Activity Monitor or a full reboot may need to be performed to ensure Forticlient is shutdown.
- Once you've confirmed that Forticlient is shutdown you'll need to start Forticlient again using the shortcut in your dock or by searching for it using spotlight.
- After Forticlient has restarted try logging in again.