Try connecting manually. Use the mongo client and see what that does using the creds that you are attempting to use.
Using your own domain for NodeBB, if your on Centos/WHM/cPanel
In your SSH, your meant to edit /usr/local/apache/conf/httpd.conf ... but DONT DO THIS!
Instead use this guide hxxp://www.zyxware.com/articles/2714/how-to-make-custom-changes-to-virtualhost-settings-in-httpd-conf-on-a-whmcpanel-vps-without-losing-the-changes [change hxxp to http, akismet does not seem to like links!]
and copy your proxy details as shown in the NodeBB docs link for configuring apache where the line begins "ProxyRequests off" copy all that info into your custom virtualhost.conf file which is stored in the custom domain folder you created.
as shown in the proxy page in the nodebb docs...
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
You might need to clear your cookies and cache for your browser to see the changes after you do the /scripts/ensure_vhost_includes --all-users command.
This is how I got mine to work, without on a normal domain.
Also things to make sure you do:
Don't install NodeBB in your public_html folder, put it in your /home/username/nodebb as it does not need to be exposed as the port number is the reason why it can work this way, making the proxy the last piece of the puzzle.
Hope this explains how to get it to work without all the hassle!!
Also if you want to boot on system start on centos, use PM2, its the only thing that actually worked!! also.. you get to use keymetrics as well!!
Im running ubuntu, i created my own startup (init.d) script so it loads on boot