Following code worked file until server IP changed. I use domain in URL.
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(@"https://example.com/oauth/token?grant_type=password&username=" + username + "&password=" + password);
request.Method = "POST";
request.Headers.Add("Authorization", "Basic ......");
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream dataStream = response.GetResponseStream();
StreamReader reader = new StreamReader(dataStream);
string result = reader.ReadToEnd();
reader.Close();
dataStream.Close();
Error:
The request was aborted: Could not create SSL/TLS channel.
But postman does it.