I’ve seen this before with Leopard upgraded users, here’s another I found:
https://echofaith.com/blog/beware-of-kcferrordomaincfnetwork-error-302/
I also have an issue accessing one of our hosts via https://speakeasy.net, and I see this as well.
Some groups are noting Safari just seems to be problematic:
https://www.flickr.com/groups/macintosh/discuss/72157605436544593/
As a hybrid, all mac, Art & IT Director, I’d say a couple things:
1) Test it out in Firefox – if it works in the fox, then you know it’s just Safari
2) You can try and reset safari’s preferences – quit safari, and go dump this file:
Harddrive > Your user folder > Library > Preferences > com.apple.Safari.plist
as well as the folder:
Harddrive > Your user folder > Library > Caches > Safari
That’ll delete some of the old preferences
If that doesn’t work, a good last ditch resort that seems to cure ills:
1) download the combo update from apple:
https://www.apple.com/support/downloads/macosx1053comboupdate.html
2) Run this, restart your compuer
That can clean out any buggy installations and start you fresh.
I’ve never seen anyone lose data doing the above, but of course, I always vouche for a backup. You can email me at brady at bradyjfrey.com if you have any other questions, but I’ll keep an eye out for this. Again, seems like it’s a desktop issue more than a server issue, but worth testing before you try my adjustments.