UPDATE:
Just came back to this as I detected the filter of Negotiator extension in chromium browser.
Track from -observatory.mozilla.org to -sshscan.rubidus.com
Consider: https://privacyscore.org/site/128404/
C+ grade security: https://observatory.mozilla.org/analyze/sshscan.rubidus.com
Error: Invalid certificate chain encountered during redirection (because sub.domain chain);
Check: https://hstspreload.org/?domain=rubidus.com
Outcome: Error: Cannot connect using TLS
polonus (volunteer website security analyst and website error-hunter)