A firewall is a possible cause. Try disabling the firewall and then setting up a VPN. If the VPN can be established well now, you need to adjust the settings of the firewall.
Another solution, and a very specific one (only for this error message!) is to download and import the ugvpn.pcf config file.
- Click 'Save'.
- Save in: select Desktop (easy to find).
- In the windows Download Complete, select 'Close'.
- In the (Cisco) VPN Client (via 'Start - Programmes - Cisco Systems VPN Client - VPN Client'), remove the existing connection entry (UGent) and then click "import" under "connection entries" in the menu.
- In the opening dialogue window select Desktop first and then the file
- Click 'Open' and 'OK' to close the window mentioning the import was succesful.