A warning is displayed in the Chrome console window regarding your certificate
The Intermediate CA has not been installed. You need to install the relevant Intermediate CA.
This error usually occurs because the website content contains both secure and insecure content.
This error can be returned by Firefox browser when your server presents a weak Diffie-Hellman key exchange.
Ensure you have installed the Intermediate CA correctly on your server.
Error produced by Firefox when visiting website secured by a no longer trusted certificate.
This error (normally presented by Firefox) means that the OCSP stapling for the site certificate is invalid.
This error indicates the certificate for the site has been revoked. If you are the site owner you can contact the certificate issuer for further information as to why this might be.