If your previous connection failed with an error, you might get this error when you try to reconnect. Select the Logout button in the Exit page to log out of the session and reconnect again.

Check to see if the Log Entries > Tunnel logs displays the following message:

No Buffer Space Available

This indicates that there is not enough buffer space. You must free memory space by closing some of the applications that are running, or by restarting the machine, then reconnecting to SSL VPN.