I should be more clear since I'm awake now
Looking back, I seriously needed some caffeine as that is one garbled partially incorrect mess.
Tried binding to solely the private IP - no avail.
With the DB server bound to 0.0.0.0 - All systems are a go.
Decided it was best to snapshot everything before I started forcing them to talk and be friendly.
Coffee Edit for @julian:
The server actually running NodeBB is accessing the server I'm using for redis over private networking, just fine. The server running redis is currently bound to 0.0.0.0 This setup works, full NodeBB functionality. It's getting these two servers to communicate to each over when both are trying to refer to each other with private IP's (binding redis to the private IP of the server running NodeBB) that I encounter an issue.
Bloody hell, I'm an idiot.
The server running redis needed to be bound in its config file to it's private IP, not the private IP of the server that would be accessing it.