When trying to connect to a Location which is another site on the same server I get the timeout error below.

Both sites are 4.7.1 with courier 2.5 full license installed.

We have ruled out a local DNS issue as the site name is resolving to the external IP address of the server. Interstingly if we set the 

Any pointers would be greatfully recieved.

System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: 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 85.159.251.65:80 
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(TransportContext& context) 
at System.Net.HttpWebRequest.GetRequestStream() 
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters) 
at Umbraco.Courier.RepositoryProviders.WebServiceProvider.RepositoryWebservice.GetAvailableRevisions(String username, String password) 
at Umbraco.Courier.RepositoryProviders.CourierWebserviceRepositoryProvider.GetAvailableRevisions() 
at Umbraco.Courier.Core.RepositoryProvider.GetAvailableRevisions(String folder) 
at Umbraco.Courier.UI.Pages.editRepository.OnInit(EventArgs e) 
at System.Web.UI.Control.InitRecursive(Control namingContainer) 
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
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 85.159.251.65:80
System.Net.Sockets.SocketException (0x80004005): 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 85.159.251.65:80 
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)