At my office I had been having a problem with my Ubuntu and Fedora boxen having problem connecting to external sites. Some would work, albeit slow, where as others would not work at all (e.g. trying to connect to reddit in Firefox would get enough of the page to display the <title></title&gt tags but it would be “forever loading” the actual content, with only a white screen).

The solution seemed to be that the router hated TCP Window Scaling. The fix that so far seems to work is to edit your /etc/sysctl.conf file and adding the line:

net.ipv4.tcp_window_scaling=0

And then running the command:

sudo sysctl -p

To reload the changes.