Did you try it with localhost like the docs say? I'm assuming you don't have to symlink it to sites-enabled like with nginx?
Also, as you're on 2.2.22 of Debian, did you do this? Looks fun...
This works for Ubuntu 12.04 as well, it took awhile but I got it to work.
Allow from all
ProxyPass /socket.io/1/websocket ws://127.0.0.1:4567/socket.io/1/websocket
ProxyPassReverse /socket.io/1/websocket ws://127.0.0.1:4567/socket.io/1/websocket
ProxyPass /socket.io/ http://127.0.0.1:4567/socket.io/
ProxyPassReverse /socket.io/ http://127.0.0.1:4567/socket.io/
ProxyPass / http://127.0.0.1:4567/
ProxyPassReverse / http://127.0.0.1:4567/
I keep it at
127.0.0.1 because nodebb is on the same server as everything else on it. Try leaving it at
127.0.0.1 and see where that gets you.