Ive followed the NordVPN Tutorials and estabished a Tunnel Connection over TCP
Re-Using the same process Tutorial for UDP, throws my Internet/routing off if both TCP and UDP tunnels are enabled. Im guessing ive missed something simple?
The tunnel itself can use either TCP or UDP, but regardless of the protocol it uses, the tunnel it establishes is the same.
From there, unless you have routing rules that change the behavior, all internet bound traffic is routed through the tunnel, regardless of protocol. In other words, both TCP and UDP data will be encapsulated and sent through the tunnel.
You can think of it like dropping off two packages at your local FedEx/UPS/< insert your preferred carrier here > store. One of them is going by ground (prenend this is TCP), the other by air (and this will be UDP). You drop them off at the store, and they will load both of them into the same truck (this is the tunnel) and drive them to the depot (which represents the remote endpoint)... at the depot, they'll handle the unique routing needs of each of the packages.
It is generally recommended to use UDP for OpenVPN (and other VPNs) because it is more efficient and can avoid something called TCP meltdown.
So with all that said, you should be able to use your Nord UDP tunnel without needing the TCP tunnel at all.