How to diagnose a mysterious network problem?

"Have you tried another computer in your house on the same internet connection (1), or your laptop on a different internet connection (2)?

I had a friend with the same issue and when he tried (1), he had the same problem and could not work out why when he took his laptop to my house, he could access a website.

I emailed the site administrator, and it turns out that he had blocked the entire IP range because someone was giving him problems.

You never know, it may be worth a try!

It could explain why DNS can resolve, but no connectivity. (just tried pinging from here and it worked)

If you have tried (2), ignore the above and I will give it another think!

Until then, if you need it urgently, try using a proxy server and see if you have any luck,

edit -- as well as that, it could be your ISP blocking it. If they have any forums, you may want to take a look. I know that I was trying to diagnose a similar problem for a good 2 days for a client and it turned out that the site was incorrectly placed on the IWF list (good in principal, rubbish in implementation), and the ISP was simply dropping all packets to the site without any warning. It got removed after I kicked up a fuss, but got no apology or explanation."