I get the error on both Firefox 59 and Safari 11.1.
curl https://hubzilla.orgreturns an SSL error, too.
On a somewhat unrelated note, is it normal to not be able to reply to most of the threads in the support forum?
"Can comment on or like my posts" is not checked for "their settings." Incidentally, I just discovered that if I visit the forums via gravizot.de instead of zotadel.net, I do see comment boxes for everything.