.NET 4.x System.Net Proxy WebException: Удаленный сервер возвратил ошибку: (403) Запрещено - C#

HttpWebRequest request = (HttpWebRequest)WebRequest.Create("http://www.2ip.ru");
request.UserAgent = "Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/43.0.2357.81 Safari/537.36";
request.Timeout = 15000;
request.Proxy = new WebProxy("186.5.75.26", 8080);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
text.Text = reader.ReadToEnd();