It's a plugin, and you can use more than one.
NodeBB and Cloudflare
I've been reading several times that NodeBB uses websockets and therefore only CF enterprise customers may use it. However my instance of NodeBB works quite fine with CF's free plan (no websocket support apparently). I also don't get any errors in my log. Why does NodeBB still work then?
If you have acceleration turned off then it works, that's probably what you have going on right now. Otherwise you'd need an Enterprise account (although I believe they are rolling it to lower plans in future). There are some other companies, one which we have worked with in the past, that also offer DDoS protection (with websocket support) with a lower price point than CF's enterprise plan
In addition, even with acceleration, the site still works, but errors show up in the server and client logs, as socket.io keeps trying to re-establish a websocket connection. The fallback connection (ajax polling) does work.
Yep, you were right. It was fallbacking to ajax polling. I guess I'm just going to use CF in DNS only mode until they release their web socket support to other plans.