node.js - Socket.io client shows Err:Empty response when many sockets are connected -

when many sockets join, server randomly throws err:empty response, browser. happens static files being served node.

i use node v5.6 , nginx v1.8 , socket.io v1.4.5. no special implementation of socket.io , nodejs. use sockets behind nginx through reverse proxy. after more 400 connections starts throwing empty response error. found similar open issue @ github.com/socketio/socket.io/issues/1925.

any step towards help.