Seems to be because of Fedora hardened policy and your site might be supporting SHA1 for use in signatures. One of the three changes with the default tweaks policy that probably makes sense https://fedoraproject.org/wiki/Changes/StrongCryptoSettings2...
When I set the crypto policy in Fedora to Legacy, which lifts those restrictions, I can visit your website.
Chrome doesn't have this problem in Fedora because it ships with its own SSL/TLS specific things bundled (or something along the lines, didn't care to get deeper in the topic).