Reason I was asking if its an H1 one and just certain HD channels is at my property an H1 wont clear certain channels without a booster, the H2 has no problems, can you try it without a splitter to rule out signal issues? As your gift supplier is pretty much correct in all or nothing....
Cable needs a sweet spot for signal, too much and no picture or picture break up, same if too low
Are you wired directly to the router too for your net connection? Also the H1 can be slow in clearing channels,