title: websocket request header miss upgrade
body: <p>I use tornado develop a websocket server, and I use nginx delegate the python server, the nginx config a server_name, and my server in Chian, and I connect the websocket server from China, it work OK, and I connect it from Australia use Wifi, it also work OK, but when I connect from Australia use 3G, it doesn't work, the request header miss upgrade node, why this happen?</p>