Webservice SocketException - Only Breaks On One Application

Question

I have a few applications which use a single Web Service which resides on the same server as the applications.

Why would only one of the applications have a problem connecting to a web service? And is there a way I can better diagnose exactly what the problem is with the connection?

It won't even connect to a web service the application itself is hosting

I have tried running it from my local machine and it works fine (updated the web ref url and the connection string to point to the liver server), which should rule out that the code itself is the problem.

I have tried setting up a different virtual directory to point to the application; and later copying the entrie app to another location on the same server and setting it up there. No luck.

[SocketException (0x274c): 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 xx.xx.xx.xx:80]
   System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress) +239
   System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP) +35
   System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception) +224

[WebException: Unable to connect to the remote server]
   System.Net.HttpWebRequest.GetRequestStream() +5321194
   System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) +103
...

Answer 1

Found it... the proxy was the cause of the issue and it is the only application where I specify proxy different from the default:

Since I only need the proxy locally I disabled it on the live web.config with enabled="false"

  <defaultProxy enabled="false">
    <proxy
      autoDetect="False"
      bypassonlocal="True"
      scriptLocation="http://www.proxy.something"
      proxyaddress="http://proxy.com" />
  </defaultProxy>