Sorry, this will be a total newbie question, and maybe not linked at all to freeflarum: someone signal me that my forum is blocked as his university (which is a problem, as it target first university teachers and students), while a lot of things are permitted there (including reddit). He said the university forbids imgur (I have the imgur upload extension), but as it is used on reddit i doubt it's the reason.
I have no idea what are the rules to decide what automatically blocks or not a website in companies or universities, and I try to find the reason, but don't know where to start. Any possibility it would be linked to the server used by freeflarum ?