If the above error happens run the following command from an elevated command prompt:
- Navigate to: C:\Program Files (x86)\Cisco Small Business\QuickVPN Client>
- openssl.exe s_client -showcerts -connect 99.99.99.99:443 >c:\temp\cert.pem
- Where 99.99.99.99 is your WAN IP.
- Make sure that there is a Temp folder under C:\
- Copy the cert.pem file from C:\Temp to the QuickVPN Client folder.
- Click Yes and through the UAC prompts if required.
- Close and re-open the QuickVPN Client
- Connect.
Original instructions here with a slight modification by us for Vista/Windows 7/8: