In Firefox,
Under Preferences>Advanced>Configure Proxies to Access Internet, what are default settings to connect to Internet? My connectivity, which had been working properly went down yesterday. I have tried varying the settings, but to no avail. My computer internet connection is working properly for other non-Firefox applications.

Would greatly appreciate some help here.

Roger Vincent

More than likely you do NOT have a proxy, hence the reason why Firefox is failing to connect to the internet.

So select NO proxy and everything should be fine.