Firefox sometimes goes offline when it detects that the connection has dropped. You can switch between offline and online using the File menu. If you show the orange Firefox button instead of the classic menu bar, you can uses the Alt key to access this feature: File ''or'' Alt+f > Work Offline If that's the problem, there is a setting you might try changing in Firefox to prevent it from automatically going offline. This thread has information about how to do that: [https://support.mozilla.org/en-US/questions/749053 Firefox keeps switching to work offline mode all by itself and therefore drops internet connection. How do I fix this?]