Bizarre timeout in Web CMS, ideas?

Question

I know this kind of thing cannot be adequately answered without a link to the live example. Unfortunately, I can't set one up right now as it's a back-end login and creating a safe public login would be too much to do at this point. Sorry. I'm hoping for ideas and input from people who may have experienced something similar in the past.

I am setting up a CMS for a client with a DSL connection in Spain.

The CMS is hosted on a straightforward standard, LAMP based, shared hosting package in a network center in Germany. It comes with a .com domain.

When my client tries to log in to the CMS using Internet Explorer 7, everything works fine. When she tries to log in using Firefox, she gets to the login form, submits it - and then the connection times out. When she logs in using Firefox but using "domain.com" instead of "www.domain.com", everything works fine.

This happens on all computers that are hooked up to that line. One Windows XP, one Windows Vista.

The front-end part of the site, as well as a second, older CMS, work fine in all browsers.

I do not have access to the raw access logs.

I have not been able to reproduce this behaviour on any other connection.

Debugging ideas are welcome. Remote diagnosis is extremely difficult as the line is too slow to set up a proper remote connection.

Answer 1

Check that Firefox and IE are using the same proxy settings.

Answer 2

DNS issues? can you put here your A records to check is everything is ok?

Answer 3

If you are limited by how you can troubleshoot this, have the client install Fiddler - Web debugging proxy and then run the trace, and send you the logs, Fiddler will analyze the traffic (be it proxy or DNS timeout, etc)

Take a look if you have not used it before:

http://www.fiddler2.com/Fiddler2/version.asp