I doubt it. I think these are for detecting whether or not you're in a "captive portal". I.e. airport wifi that requires you to enter login credentials or somet

I doubt it. I think these are for detecting whether or not you're in a "captive portal". I.e. airport wifi that requires you to enter login credentials or something. But hey, give it a whirl: block detectportal.firefox.com with your hosts file and see what happens.