访问HTTPS网站，因SSL协议问题，导致请求立即断开连接

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。

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;