Can't open more than x sockets with server from a single client...

[jondubois]

Thanks to Cyrus for notifying me of this issue:

Basically, when trying to stress test SocketCluster with a single client, you might run into the issue of new sockets not connecting past a certain number (e.g. 20).

[jondubois]

This is a security feature of SocketCluster designed to prevent malicious clients from hogging up unlimited connections (and DOS-ing your server).

If you want to get rid of the limit, set the addressSocketLimit start option to 0.
I.e:
new SocketCluster({
...,
addressSocketLimit: 0
}).

It's probably best to have a limit set when running your server in production though. This is a gotcha of using the stateful WebSocket protocol.

If you have a good firewall (that handles WebSockets properly) or you've written some protective code in your balancerController file then it might be safe to set addressSocketLimit to 0. The addressSocketLimit option is just SocketCluster's default way of handling the problem.