https://www.cnblogs.com/eastday/p/6043631.html

postman没问题，代码请求就报错：由于远程方已关闭传输流,身份验证失败
Fiddler抓包发现是 ssl安全传输协议 不一样不一致造成的错误

手动指定特定的安全传输协议
HttpWebRequest myRequest = (HttpWebRequest)WebRequest.Create(serviceUrl);
//ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
//ServicePointManager.SecurityProtocol = (SecurityProtocolType)192 | (SecurityProtocolType)768 | (SecurityProtocolType)3072;
//4.5版本以上可使用：ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11;
HttpWebResponse myResponse = (HttpWebResponse)myRequest.GetResponse();