Am unsure of cause. I have Dish Network and I have TV2 coming out to a TV. It goes through a 2-way splitter first then to TV (This TV's picture is great but is only 3 feet from splitter.)and other line goes to upstairs where it splits into another 2 lines. The picture is fuzzy only upstairs. Thought it was TV but we tested 3 different TV's and got same result. Then we replaced all the cable and splitters. Same result. Do I need a signal booster to get good picture?