hello, first please make sure that the date & time is set correctly on your system.
if this doesn't solve the issue (or it is already set properly), could you tell us which error code is shown under technical details on the error message and when you inspect the certificate which issuer information it does contain (see screenshot)?

"This Connection is Untrusted" error message appears - What to do

Check out why the site is untrusted (click "Technical Details to expand that section) and if this is caused by a missing intermediate certificate then see if you can install this intermediate certificate from another source.

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer of the certificate.

You can see more Details like intermediate certificates that are used in the Details pane.

If "I Understand the Risks" is missing then this page may be opened in an (i)frame and in that case try the right-click context menu and use "This Frame: Open Frame in New Tab".

Note that some firewalls monitor secure (https) connections and send their own certificate instead of the website's certificate.

• ESET Setup -> Advanced setup -> Web and email -> Protocol filtering -> SSL
• Certificates: Add the root certificate to known browsers

See also:

• SSL protocol: Do not scan SSL protocol