This isn’t super helpful here because if this is an issue for you then you can’t read this here on the forum, but I thought I’d add this information for people who know or hear of anyone using a Mac running OS X 10.11 or earlier that’s having trouble accessing the forum, and other web sites lately.
As of September 30th 2021 the SSL Certificates in the operating system expired, and as the result users of OS 10.11 and earlier can’t get to many common places on the web - Isla Instruments (site or forum) Reverb, and many more. This is true with Chrome, Safari, and all the other browsers I tried.
They sort of warned us, but I didn’t understand the warning. It seemed more like a marketing pitch to get me to update my OS (which I don’t plan to do) so I ignored it. We CAN manually update these certificates 30 days before they expire, but once they expire then we can’t anymore.
Open Keychain app, unlock the panel so changes can be made and view the certificates in there by date. You’ll see a long list of expired SSL Certificates.
For each certificate, set the Trust settings to “always trust”
I recommend you take a look at each certificate you’re setting this way, and make sure they are legit, apple have a list of all their certificates for each OS so you’ll know if it’s legit or not.
Once that’s done then there are three Certificates which must be downloaded and added to the System level of the keychain:
With this all done, Macs using 10.11 and earlier should now work properly again, and all is well.
This post is evidence of that. Yaay!
For more about these files, and links to download them:
This article (after reading many) helped solve the problem:
I hope this helps people out.