Can anyone having this problem let me know if you're on a school, work, or home network? I'm not able to find anything at all in our logs pointing to this problem, I've verified again that all servers have valid SSL certificates available for cPanel, and that none of your IP addresses or networks are blocked by the server firewalls. All that I can think of at this point is that something on your network or computers are attempting to restrict or "man in the middle" your connections to the non-standard cPanel port and it's leading to the browser errors. For those experiencing the problem, are you able to access your websites while this cPanel problem is happening? (Jessica.C and rue42x10 I see you've already answered this, thank you.) If you're able to access the website this suggests the problem is only relating to cPanel on the non-standard port 2083 and that it isn't a connectivity problem to the overall server or our network. In the past I've seen that some antivirus programs and school networks block access to ports like 2083, but this is pretty peculiar since it started happening for multiple people around the same time (end of December) once across multiple servers.