we were in the technical problem since since last couple of the days. we googled it a lot , however after all we have done it today 
. special thanks to Jigar Pandit for the same.
Problem:
Web service call is working fine in our local system. however when we installed middle-tier service (which contains dll of web-service call) on remote server. it started giving “The underlying connection was closed: Unable to connect to the remote server.“ Error.
Description
This problem may occur when one or more of the following conditions are true:
| • | A network outage occurs. |
| • | A proxy server blocks the HTTP request. |
| • | A Domain Name System (DNS) problem occurs. |
| • | A network authentication problem occurs. |
Resolution
To resolve this problem, make sure that the proxy settings are correct. To do this, use the following techniques:
| • | Use the static WebProxy.GetDefaultProxy method. For more information, visit the following Microsoft Web site:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemnetwebproxyclassgetdefaultproxytopic.asp (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemnetwebproxyclassgetdefaultproxytopic.asp) |
| • | Define a <proxy> element in the application configuration files. For more information, visit the following Microsoft Web site:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/gngrfproxyelement.asp (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpgenref/html/gngrfproxyelement.asp) |
| • | Configure the .NET client to use HTTP 1.0 by changing the HttpWebRequest.ProtocolVersion property. For more information, visit the following Microsoft Web site:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemnethttpwebrequestclassprotocolversiontopic.asp (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpref/html/frlrfsystemnethttpwebrequestclassprotocolversiontopic.asp) Note By default, the .NET Framework uses HTTP 1.1. |
Out of this 3 option, first one works for us.
Reference Taken From
http://support.microsoft.com/kb/915599/en-us
Posted by nilangshah 
