They won't do two Superhubs at the same property.
The only way for OP to do it is either via a cat 5 cable, powerline plugs, or wi-fi. He can move the superhub downstairs and connect directly, but then he has to use the same connection methods to go back to (presumably) where his PC is.
It doesn't work that way. It's like asking why you can't cook your dinner out of the gas line that goes to your boiler, because your oven is in another room. The Superhub is the termination that comes into the house and from there everything else flows. You need the SH to decode the internet off the cable, you can't get a signal off it otherwise.
Right, I understand now! Thanks for the information and your patience.