Hi Sasuke92
You don't need a second ethernet connection between your VM set top box and the hub, in fact the VM set top boxes only have one ethernet port.
If you have the VM Stream box then the ethernet connection from the Stream box to the VM hub will allow you to watch live TV carried over the internet, and also access apps and catch up services, that connection also updates the EPG and is also used to perform box updates.
If you have a VM TV360 box then you need to attach the white coaxial cable to that box as it allows you to watch live TV channels. The ethernet connection between the hub and the VM TV 360 box allows you to access apps and catch up services, but it also updates the EPG and is also used to perform box updates.
If you have a good wireless signal then you could connect the VM Stream box and the TV360 set top box via wifi instead of using an ethernet cable.
If you have a smart TV then you can connect that to your VM either by ethernet cable or wifi so you can use the internet services on your smart TV.