"A connection attempt failed because the connected party did not properly respond after a period of time" using WebClient

I am using the following code which is working on local machine, but when i tried the same code on server it throws me error

A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond

Here is my code:

WebClient client = new WebClient();
// Add a user agent header in case the 
// requested URI contains a query.
//client.Headers.Add ("ID", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)");
Stream data = client.OpenRead("http://" + Request.ServerVariables["HTTP_HOST"] + Request.ApplicationPath + "/PageDetails.aspx?ModuleID=" + ID);
StreamReader reader = new StreamReader(data);
string s = reader.ReadToEnd();
Console.WriteLine(s);
data.Close();
reader.Close();

I am getting error on

Stream data = client.OpenRead("http://" + Request.ServerVariables["HTTP_HOST"] + Request.ApplicationPath + "/PageDetails.aspx?ModuleID=" + ID);

is it due any firewall setting?

I had a similar problem and had to convert the URL from string to Uri object using:

Uri myUri = new Uri(URLInStringFormat, UriKind.Absolute);

(URLInStringFormat is your URL) Try to connect using the Uri instead of the string as:

WebClient client = new WebClient();
client.OpenRead(myUri);

setting the proxy address explicitly in web.config solved my problem

<system.net> 
    <defaultProxy> 
            <proxy usesystemdefault = "false" proxyaddress="http://address:port" bypassonlocal="false"/> 
    </defaultProxy> 
</system.net>

Resolving the “TCP error code 10060: A connection attempt failed…” while consuming a web service