Hopefully this will help other owners that are having difficulty connecting a portable satellite to their 2015 Precept 31UL. We use Direct TV so we ordered a King portable satellite to use when air or cable were not available. I don't believe it makes any difference on the external connection because this is a mistake at the factory on getting and external signal into the coach.
I started by connecting to the coaxial connection located on the exterior drivers side rear cabinet. This is where the outside shower and water controls are located. We connected the coaxial port from the portable satellite and no signal on the inside connections. The inside connections are located behind the bedroom TV in the rear of the coach. This is when I called Jayco customer service. They were prompt, pleasant and nice to deal with, however they didn't really answer the question. Where does the exterior coaxial cable terminate in the coach.
We purchased a coaxial tester at Home Depot and started the search. Pulled all of the cable plates out and started testing. I found the black coaxial cable from the exterior connection hooked up to the TV antennae connection in the back of the switch plate. This didn't make sense because the TV antennae connection has a 12v booster on it and would block an external signal. There was a Satellite connection/port with no cable attached just above the TV connection/port. I disconnected the black cable from the TV connection/port and connected to the Satellite port. I then connected this to the Direct TV receiver and then connected to the grey coaxial that connects to all three TV's.
I don't have pictures to show the exact connections but they are located behind the bedroom TV. We live 2 hours from our dealer so it was worth the time and effort to do this at home. Bottom line, during the production of the coach someone connected the exterior cable to the TV port not the Satellite port.
The manual doesn't clearly describe the sound/AV options and connections. This forum helped us work through this issue and many thanks to the members. We love our 31UL and are much happier now this is resolved.
Safe travels to all