webApi Authentication failed because the remote party has closed the transport stream身份验证失败了，因为远程方关闭了传输流。

public class CertificateTrust
    {
        public static void SetCertificatePolicy()
        {
            //当在浏览器中可以正常访问，而code中出现错误时，可以用fiddle看下正常访问的SSl加密认证的版本号
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
            ServicePointManager.ServerCertificateValidationCallback = 
                new System.Net.Security.RemoteCertificateValidationCallback(CheckValidationResult);
        }
        public static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true;
        }
    }

连接client之前调用

CertificateTrust.SetCertificatePolicy();