I was using Firefox 56 yesterday with no issues. It apparently upgraded in the background to Quantum, and now it won't connect to any websites. I CAN connect to internal pages (like my printer and router), but any external pages generate a "Server Not Found" message. I'm on Mac 10.13.1, and both Chrome and Safari connect with no issues. I've: * Deleted and reinstalled Firefox * Deleted the Library/Application Support/Firefox folder and Firefox, emptied the trash and reinstalled from a new download * Followed the instructions (here: <https://support.mozilla.org/en-US/kb/server-not-found-connection-problem#w_firefox-cannot-load-websites-but-other-browsers-can>) to set the browser to "No Proxy" (like my other browsers), turned off DNS Prefetching and disable IPv6 * Performed a "Firefox Refresh" Again, the other browsers work fine. It's just Firefox Quantum. (And I tried downloading and installing 56.0.2, which worked perfectly yesterday, and now it does the same thing.