Can you resolve google.com via the about:networking DNS Lookup tool&nbsp;? You can check the connect

Can you resolve google.com via the about:networking DNS Lookup tool ?

You can check the connection settings and check for possible issues with a Proxy or VPN service.

Settings -> General -> Network: Connection -> Settings

If you do not need to use a Proxy to connect to internet, select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly.

See also:

https://support.mozilla.org/en-US/kb/connection-settings-firefox

https://support.mozilla.org/en-US/kb/websites-dont-load-troubleshoot-and-fix-errors