Your Request Headers
Do you have an experience to make a network connection always failed but with other apps worked? It's a little frustrated to have such kind of experience.
When debugging my app, I met the same issue that with Android HttpURLConnection failed but with wget worked. To know what's the difference between them. I had created a page to dump all request headers your client agent sent.J
Just follow the link: http://ts2.miidio.com/dump-headers.php to get all your headers sent. It's useful because it dumps header with separated by '\n' when call this in the console or in your app.
Have fun with it.