There a few threads on this topic.
I had the same problem. On my unit Jayco never connected the negative wire to the wall plate.
Here is what I found in the panel behind the wall plate:
Grey and Red were joined at the spade connector.
White is in the power -
Black was flapping in the breeze (with a spade on it).
Had testing with the DVM Proper wiring should be as follows:
Red wire Wifi +
Black wire Wifi -
Grey wire Power +
White wire Power -
Winegard was kind enough to send me the plate that comes with the unit, so I installed that. I had to separate the Red and Grey and put on new spade connectors.
Now I have the button for Ant/Cable and a button for wifi. All is working well.
Alternatively I could have joined the black and white with a new spade connector.
Here is the other threads: