The website are running on the same machine as Firefox, while IE and Edge can run those fine, Firefox is unable to resolve the address since I updated it's version (I failed the rule of never update if it's working :/ ). I've cleared the cache, tried all the suggested and unsuggested proxy settings, uninstalled and clear EVERY Firefox file from the computer. Even with a fresh Install Firefox cannot acces any of the locally hosted domain. The domains are setted up inside Windows hosts file. The domains are all locally hosted and run. They were working fine before I updated Firefox. They are working fine on IE and Edge. Firefox tries to load the the domain in HTTP then HTTPS when it fails to connect. The domain uses a custom extension "dev". I have no extension on my Firefox. Again, it was working fine before the update, after the update restart all of it was dead. BEen tackling this issue for a third day now and cannot work. Thank you