Mozilla Firefox: cannot open


I cannot open the with Firefox (latest version). I use a hardened Firefox that is based on ghacks userscript/Librefox SSL/TLS settings. So it uses only TLS 1.3. 

I ran a SSL test ( and noticed that TLS 1.3 is not supported. I can perfectly browse to other Sophos sites with Firefox.

Will the community site support TLS 1.3 in the near future?

Kind regards.