Update:
Still no change regarding CAC access; unable to access sites via CAC
On at least two .mil sites I'm getting similar error messages:
"Safari can't open the page "https://xxxxxxxxxx" because the server unexpectedly dropped the connection. This sometimes occurs when the server is busy. Wait for a few minutes and then try again."
What is interesting is that I'm getting the same message whether the CAC reader is plugged in or not when trying to access these sites. But, I can see the proper CAC Keychain and certificates when the CAC reader is plugged in with the CAC inserted. In layman terms, it seems as if the websites can't 'see' the CAC and certs even though they are quite visible on the computer itself???
I hope I haven't confused the issue.