Running a basic node.js + express + socket.io setup, I would occasionally get ECONNRESET errors. After a bit of trial and error, I found that this seems to have been caused by running socket.io and express on the same port, port 80.
I opened up port 81 on the server, and ran socket.io through port 81. My code to set things up now looks like:
var httpPort = 80; var socketIOPort = 81; var express = require('express'); var app = express(); app.listen(httpPort); var socketIO = require('socket.io'); var io = socketIO.listen(socketIOPort);