Can't access aetna site or webpages
I'm using an iMac w El Capitan, and all the latest updates. Can't access any Aetna website or webpage. Get an Aetna OOPS msg. Tried using Safari, FFox, and Chrome. Aetna is the only site I can't get to. Tried re-booting, and also flushed DNS cache. Problem does not appear to be w Cox's DNS servers. Also tried resetting IpV6 to local-link only, from automatic. Latest Java release installed yesterday. Using Norton, but no applicable firewalls which would impact Aetna. Any suggestions?
iMac (21.5-inch, Late 2013), OS X El Capitan (10.11.4)