My network layout is as follows:

A GNU/Linux server acting as router connects to the internet through PPPoE. On a second interface a switch is connected. On this switch 2 computers are connected, a Laptop and a Desktop. The laptop runs Windows XP Professional, the desktop runs Windows Vista. Both backend machines get configured through DHCP running on the GNU/Linux server.

The problem is that the desktop is unable to make a successful connection to certain websites while the laptop is able to connect to these sites. If I hook up the laptop to the cable attached to the desktop it is still able to connect to those sites, so it is not the cable.

One of the sites the desktop is unable to connect to is FAIL Blog. It keeps on loading, and never finishes. It does download the main HTMLpage, but it stales completely on the http://s2.wordpress.com host which serves some of the files. It appears to be mostly related to CDN hosts.

It doesn't matter which browser I use. And there is no special firewall software running on the desktop. The hostnames resolve as they should.

Does anyone have an idea what could be the cause of this problem?

3 Answers 3


Have you checked to see if you are having problems connecting, or if it is actually having a problem resolving the hostname? Check your network settings, and you can use nslookup to check to see if your Desktop is able to resolve the hostname (for example, s2.wordpress.com).

Since one works and the other doesn't - I am betting that the desktop is not configured properly. Unless you have some sort of other problem in your DHCP/Linux server, but without knowing details it is impossible to say.

  • Forgot to mention that, hostname resolving works fine.
    – elmuerte
    Nov 6, 2009 at 20:40
  • What happens if you telnet directly to that IP then? Nov 6, 2009 at 21:07
  • I get an instant HTTP 400 Bad Request response and the connection is closed. Which is weird, because the connections the browser makes remain open forever (according to TCPview).
    – elmuerte
    Nov 6, 2009 at 21:36

Personally I would look at the browser, its settings, add ins, etc. If it is IE, is the version the same on both PC's? Have you tried Firefox? If so, how about some of the add-ins that can help you to troubleshoot issues. Y-Slow, tweak network, etc. If you do not want to try alternate browsers, maybe try to see how a program like wget works for pulling down the site? If it works fine, it is most likely something in your browser settings somewhere. If not, lower into your IP stack, maybe anti virus or anti spyware settings gone bad. Adblock software?

  • As I said it doesn't matter what browser I use. Firefox, MSIE, Chrome, Safari all have the same problem. Wget sits there with "HTTP request sent, awaiting response...".
    – elmuerte
    Nov 7, 2009 at 8:21

After a lot of debugging I finally figured it out. The MTU of my backend host was too large. Weird that this was only an issue with certain hosts.

I used the info on this site to update the MTU on my Vista workstation.

Just in case the site disappears, I executed this:

netsh interface ipv4 set subinterface "Local Area Connection" mtu=1464 store=persistent

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