错误信息：
InnerException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.
Message: The underlying connection was closed: An unexpected error occurred on a send.
解决方案：
在发起请求的地方加入如下SSL相关设置。
1 ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;