What is the exact error when you receive the "Secure connection failed"?

• Secure connection failed and Firefox did not connect

Since you also reported a website not appearing as it should also see:

• Websites look wrong or appear differently than they should

Please post back, did this help?

A common reason for secure certificate errors is that Firefox is not set up to work with a feature of your security software that intercepts and filters secure connections. In that process, the software presents Firefox with a "fake" certificate for the site, so until Firefox is set up to trust the software, it will always object to those certificates. Software with this feature includes avast! 2015, ESET, Kaspersky, and BitDefender.

Unfortunately, these errors also can be caused by malware, so rather than add exceptions, let's investigate.

Since you create an exception for this support site, please check the "Issued by" information for the certificate to see whether that points to the source of the problem. To do that, you can click the padlock (or gray warning triangle) in the address bar, then More Information, then View Certificate. I have posted a screen shot for comparison. What do you see in the red-boxed areas?

If you can't inspect the certificate via "I Understand the Risks" then try this:

Open this chrome URI by pasting or typing this URI in the location/address bar to open the "Add Security Exception" window and check the certificate:

• chrome://pippki/content/exceptionDialog.xul

In the location field type/paste the URL of the website

• retrieve the certificate via the "Get certificate" button
• click the "View..." button to inspect the certificate in the Certificate Viewer

Check who is the issuer of the certificate.

You can inspect more details like the certificate chain in Details tab of the Certificate Viewer.