The requested domain name is not configured for any web site:
https://connect.mandela.ac.za:443/Blogs/MiPad---me-and-my-iPad-2/April-2012/Setting-up-a-VPN-connection-for-your-iPad
If you're an administrator of this site, you need to go to
Site Manager -> Sites
and use the following domain name either in the Site properties or add a new domain alias:
connect.mandela.ac.za:443