When browsing the web, certain sites sometimes refuse to load, or sit waiting for up to 20-30 minutes and then suddenly appear. The problem is intermittent, the same site might load instantly a few hours later. Certain other sites seem to always work.
When this happens, I can ping and traceroute the affected URL without any problems. I also installed Wireshark and captured the network traffic. The relevant TCP stream looks like this:
https://dl.dropboxusercontent.com/u/4084480/wireshark_dump.png
avarice.home is my computer and www.numark.com the site I was trying to connect to. As can be seen, the initial TCP handshake completes fine, but as soon as my browser sends a http GET, nothing more happens. Until the remote site at time 15.56 sends a TCP packet with a much too high sequence number (21301, displayed in the screen shot). It's as if all the intermediate response packets just disappeared somewhere. From that point on, all that happens is a bunch of keep-alive messages until I stop the capture.
Has anyone got any pointers about how to troubleshoot this? I've never come across an issue like this before.
A few more details:
* Machine is Windows 7 using a USB wireless adapter which connects through an ADSL cable modem/router.
* Browser used is irrelevant, both Chrome and Firefox exhibit the behaviour.
* Other devices (a laptop, an iPad) connecting through the same router do not seem to be affected.
* Wireshark showed that browser initiated the request by sending out 5 SYNs to www.numark.com on different ports, is this normal?
* I have not been able to test with a wired connection (simply don't have a long enough LAN cable) yet.
Thanks for reading.
When this happens, I can ping and traceroute the affected URL without any problems. I also installed Wireshark and captured the network traffic. The relevant TCP stream looks like this:
https://dl.dropboxusercontent.com/u/4084480/wireshark_dump.png
avarice.home is my computer and www.numark.com the site I was trying to connect to. As can be seen, the initial TCP handshake completes fine, but as soon as my browser sends a http GET, nothing more happens. Until the remote site at time 15.56 sends a TCP packet with a much too high sequence number (21301, displayed in the screen shot). It's as if all the intermediate response packets just disappeared somewhere. From that point on, all that happens is a bunch of keep-alive messages until I stop the capture.
Has anyone got any pointers about how to troubleshoot this? I've never come across an issue like this before.
A few more details:
* Machine is Windows 7 using a USB wireless adapter which connects through an ADSL cable modem/router.
* Browser used is irrelevant, both Chrome and Firefox exhibit the behaviour.
* Other devices (a laptop, an iPad) connecting through the same router do not seem to be affected.
* Wireshark showed that browser initiated the request by sending out 5 SYNs to www.numark.com on different ports, is this normal?
* I have not been able to test with a wired connection (simply don't have a long enough LAN cable) yet.
Thanks for reading.
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