One fine day when I tried to connect to one of my staging report server I got the

“Unable to connect to remote server error”

I checked the report services & sql server (to which SSRS is mapped) services and both of them were running. I tried to connect to the report server thru configuration tool and that also worked fine.

SSRS log file had reported some more error

ui!ReportManager_0-1!12c0!05/24/2011-06:28:25:: e ERROR: Unable to connect to the remote server
ui!ReportManager_0-1!12c0!05/24/2011-06:28:25:: e ERROR: HTTP status code –> 500
——-Details——–
System.Net.WebException: Unable to connect to the remote server —> System.Net.Sockets.SocketException: Only one usage of each socket address (protocol/network address/port) is normally permitted 127.0.0.1:80

   at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)

  at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)

   — End of inner exception stack trace —

   at System.Net.HttpWebRequest.GetRequestStream()

   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)

   at Microsoft.SqlServer.ReportingServices2005.ReportingService2005.GetPermissions(String Item)

   at Microsoft.SqlServer.ReportingServices2005.RSConnection.GetPermissions(String Item)

   at Microsoft.ReportingServices.UI.Permissions.GetPermissions()

   at Microsoft.ReportingServices.UI.Permissions.CurrentUser(String itemPath)

   at Microsoft.ReportingServices.UI.ReportingPage.get_RSUser()

   at Microsoft.ReportingServices.UI.FolderPage.Page_Init(Object sender, EventArgs e)

   at System.EventHandler.Invoke(Object sender, EventArgs e)

   at System.Web.UI.Control.OnInit(EventArgs e)

   at System.Web.UI.Page.OnInit(EventArgs e)

   at System.Web.UI.Control.InitRecursive(Control namingContainer)

   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
appdomainmanager!ReportManager_0-1!ecc!05/24/2011-06:28:36:: e ERROR: Remote certificate error RemoteCertificateNameMismatch, RemoteCertificateChainErrors encountered for url https://localhost/ReportServer/ReportService2005.asmx.

I restated both SQL & SSRS services but of no help. One thread in MSDN forum was saying that this might be due to SSL configuration and the solution is to disable SSL. But my server was  not configured for SSL. nevertheless I checked my config. file to see whether someone enabled the SSL but found no updates to the config file.

My colleague in infrastructure team said the error

Only one usage of each socket address (protocol/network address/port) is normally permitted 127.0.0.1:80

normally indicates that the port might be used by more than one application or might it have been blocked. And he found that Windows Firewall is enabled on the Staging server and turning off it fixed this issue.