If you are on comcast/xfinity internet they have censored certain websites by making an "advanced security" feature the default setting. You are able to change this in the xFi settings area. Also you should be able to load the main catbox.moe website itself, just not files from it, on the main website itself they have a notice at the bottom of the page about xfinity/Comcast essentially censoring them and others via this method, and a link on how to change it.