The requested domain name is not configured for any web site:
https://connect.mandela.ac.za:443/Forums/f11/t65/AcerEdu-discounts?mode=quote&replyto=66
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