My website is labelled as "Not Secure" only on Chrome in Windows 10.
I can open the same page in Firefox / Windows 10 and also in any browsers including Chrome on Mac.
Developer tools show it is a Certification Error.
I clicked View Certificate button, which tells “This certificate cannot be verified up to a trusted certification authority.
This
CA Root certificate is not trusted. To enable trust, install this
certificate in the Trusted Root Certification Authorities store.
When I checked Certification Path tab, the following shows up.
x VeriSign Universal Root Certification Authority
(This CA Root certificate is not trusted because it is not in the Trusted Root Certification Authorities store.)
Symantec Basic DV SSl CA - G2 (This certificate is OK)