It seems to be that. I had initializaed a new profile in firefox and played with some options in about:config and somehow the option security.ssl.require_safe_n

It seems to be that. I had initializaed a new profile in firefox and played with some options in about:config and somehow the option security.ssl.require_safe_negotiation was set to true. All this week this was the first website to fail because of that. It works with it set to false.