Dim HTTPreq As HttpWebRequest
 
Try
   'Mit www Adressen kein Fehler
   HTTPreq = WebRequest.Create("http://www.google.de")
 
   'ohne www Fehler 403
   'HTTPreq = WebRequest.Create( 
   ' "https://filterdb.iss.net/urlcheck/url-report-dboem.asp?fullurl=") 
 
   HTTPreq.Proxy = New System.Net.WebProxy("192.168.123.456:8080")
 
   Dim webResponse As Net.HttpWebResponse = HTTPreq.GetResponse() '<<Hier Tritt 
   ' der Fehler auf
   Dim sr As New StreamReader(webResponse.GetResponseStream())
   Console.WriteLine(sr.ReadToEnd().Trim())
 
Catch ex As Exception
 
   Console.WriteLine(ex.Message)
End Try
 
Console.ReadLine()