Authentication issues wih proxy?

[G_Waddell]

Hi All,
I think I maybe falling victim to the "double hop"!
We have a windows form program that uses a 3rd party web service to validate bank details (BIC, IBAN etc.)
It uses a class we developed that creates a uri and passes it through the firewall upto the service provider.
We were asked to provide similar functionality on our Intranet so we created a webforms page that points to the same original class. The problem is when the Windows form runs the class, it motors along and returns an answer in seconds, when the ASP.NET page calls the class however, it times out with an error saying it can not connect to the remote server.
I suspected an authentication issue so I wrote new class that inherits from the original class but Impersonates the current user for the web. However, this is still displaying the same behaviour.
Here is my "Web Class" code (with security redactions of course!)

Private Function SendRequest(uri As String, objResponse As String, ByRef theresult As Object) As Boolean
        Dim iUsername As String = "USERXXXX"
        Dim iPassword As String = "XXXXXXXXXXXXXX"
        Dim wrGETURL As WebRequest = Nothing
        Dim cc As System.Net.CredentialCache = Nothing
        Dim theProxy As IWebProxy = Nothing
        Dim wi As WindowsIdentity = Nothing
        Dim CTx As WindowsImpersonationContext = Nothing
        Try
            'Get current User
            wi = System.Web.HttpContext.Current.User.Identity
            'Impersonate the current user... 
            CTx = wi.Impersonate
            ' Connection is established
            wrGETURL = WebRequest.Create(uri)
            theProxy = wrGETURL.Proxy
            If Not IsNothing(theProxy) Then
                theProxy.Credentials = CredentialCache.DefaultCredentials
            End If
            wrGETURL.PreAuthenticate = True
            cc = New System.Net.CredentialCache
            cc.Add(New Uri(uri), "Basic", New System.Net.NetworkCredential(iUsername, iPassword))
            wrGETURL.Credentials = cc
            ' Objects reading response content are created
            Dim objStream As Stream
            objStream = wrGETURL.GetResponse.GetResponseStream()
            Dim objReader As StreamReader
            objReader = New StreamReader(objStream)

            ' Response content is stored into a variable

            objResponse = objReader.ReadToEnd()
            Select Case (TheAction)
                Case (0)
                    Dim prev As Get_Details_of_a_BIC_result = JsonConvert.DeserializeObject(Of Get_Details_of_a_BIC_result)(objResponse)
                    theresult = objResponse.ToUpper.Replace("{", "").Replace("}", "").Replace("[", "").Replace("]", "").Replace(""",", vbCrLf)
                Case (1)
                    Dim prev As Check_the_Validity_of_a_BIC = JsonConvert.DeserializeObject(Of Check_the_Validity_of_a_BIC)(objResponse)
                    If prev.validity = "IBIC" Then
                        theresult = "FALSE.1"
                    Else
                        theresult = "TRUE"
                    End If
                Case (2)
                    Dim prev As Check_the_Validity_of_a_BIC_With_Date = JsonConvert.DeserializeObject(Of Check_the_Validity_of_a_BIC_With_Date)(objResponse.Replace("{""status"":", "").Replace("},""bic""", ",""bic"""))
                    If prev.validity = "IBIC" Or prev.user_message = "Invalid date parameter" Then
                        theresult = "FALSE.2"
                    Else
                        theresult = "TRUE"
                    End If
                Case (3)
                    Dim prev As Get_the_LEI_for_a_BIC = JsonConvert.DeserializeObject(Of Get_the_LEI_for_a_BIC)(objResponse.Replace("{""status"":", "").Replace("},""bic""", ",""bic""").Replace("}}", "}"))
                    If prev.user_message.Contains("No corresponding LEI found") Then
                        theresult = prev.user_message
                    Else
                        theresult = prev.lei
                    End If
                Case (4)
                    Dim prev As Get_the_National_IDs_for_a_BIC = JsonConvert.DeserializeObject(Of Get_the_National_IDs_for_a_BIC)(objResponse)
                    If prev.USER_MESSAGE.Contains("NO CORRESPONDING NATIONAL ID FOUND") Then
                        theresult = prev.USER_MESSAGE
                    Else
                        theresult = prev.id
                    End If
                Case (8)
                    Dim prev As Check_the_Validity_of_a_iban = JsonConvert.DeserializeObject(Of Check_the_Validity_of_a_iban)(objResponse.Replace("{""status"":", "").Replace("},""iban""", ",""Iban"""))
                    If Not prev.validity = "IVAL" Then
                        theresult = "FALSE.3"
                    Else
                        theresult = "TRUE"
                    End If
                Case (9)
                    Dim prev As Get_BIC_From_IBAN = JsonConvert.DeserializeObject(Of Get_BIC_From_IBAN)(objResponse)
                    If prev.BIC.Contains("NO CORRESPONDING NATIONAL ID FOUND") Then
                        theresult = prev.BIC
                    Else
                        theresult = prev.BIC
                    End If
                Case Else
                    theresult = objResponse.ToUpper.Replace("{", "").Replace("}", "").Replace("[", "").Replace("]", "").Replace(""",", vbCrLf)
            End Select

            ' Objects reading response content are destroyed
            objReader.Close()
            objStream.Close()

            Return True

        Catch ex As Exception
            'Errors.displayError(ex.ToString, Errors.displayErrorType._Error)
            If ex.ToString.Contains("(400)") Then
                theresult = "FALSE"
            Else
                theresult = "'https://www.swiftrefdata.com/ws/'" & vbCrLf & vbCrLf & vbCrLf & ex.ToString
            End If
            Return False
        Finally
            'Stop impersonating the current user
            If CTx IsNot Nothing Then
                CTx.Undo()
            End If
        End Try
    End Function