I suspect he is getting the VHF station since it is in the same direction the antenna is pointed and the UHF station is weaker, 1edge, and not in front of the antenna. In a
reddit thread, a guy with a similar problem fixed it by adding a y5-7-13. The ANT751R only has 5db gain. Before going on the roof, I would consider adding a
Stellar Labs 30-2476 via a
UVSJ. The manual says it has 10-14db gain -- at least twice what your antenna has.