There seem to be some issues with the SSL certificate for www.ffsmk.org in Firefox.Websites prove their identity via certificates, which are valid for a set time period. The certificate for www.ffsmk.org expired on 1/8/2017.
Firefox seems to be a bit stricter about these things as Chrome does let me get to the site but has the little "Not Secure" warning in the address bar.Edit: The problem seems to exist between the chair and the keyboard
. I still had some shitty HTTPS extension running in Firefox. Removing that fixed it.