I've been using DirectTv without a landline for 5+ years. In our new house I needed to get Ethernet wireless dongles. They plug into the back of the DirectTv box and then connect to our wireless router. In our other house the networking gear was in the same cabinet as the DirectTv box and I just used a Ethernet cable.
DirectTv did our recent install for us, I got the Ethernet wireless adaptors at BestBuy.