If your VPN isn't connecting, chances are that your antivirus signatures are out of date and need to be updated.
Click the Symantec logo in the menu bar at the top of the screen. Then click Live Update/Open Live Update.
From there, you'll see a pop up window prompting you to check for updates. Click "Update Now", and Symantec will check for the latest antivirus signatures and install them on your machine. It will give you a prompt when it's done, just click "Ok" and close out of Live Update.
Click the up arrow on the right side of the task bar at the bottom of the screen. Right-click on the Symantec shield logo, and select Open Symantec Endpoint Protection.
On the right side of the Symantec window, click on Live Update.
This will launch the Live Update session. When it is done updating the antivirus signatures, the button on the lower right side of the window will change from Cancel to Close. Click Close and exit the Symantec Endpoint Protection window.