Cannot access OGS domain on MacBook

According to Safari, I have been unable to obtain a secure connection since the recent OGS update. Firefox gives the same result but Opera and Vivaldi work. I posted these reports:

cant-connect-using-safari-as-of-update-this-week-secure-connection-fails

opera-developer-tools-reports-issues-with-sites-certificate-chain

I use Avast Mac Security for AV. What do you use?