I have an 18ft by 9 ft led panel tv how do I get the picture to show up

I have a large panel tv on my patio outside. It shows my apple tv, Netflix etc perfectly, I go to DirecTV and the picture is only half the screen. How do I hook this up to show the full screen? I have changed the box and the cords and it still only shows half a screen. This is my business I need this to work help!