(vs2015)I can link to server in debug mode,but when I use release mode,it can't work

Stream newStream = request.GetRequestStream();

When I run the code in debug mode.It works well and I can get information from server.But when I use release mode, it crashes.

The warning infomation: An unhandled exception of type 'System.Net.WebException' occurred in System.dll

Additional information: Unable to connect to the remote server

via Chebli Mohamed