Current setup is cable TV and Internet run through a cable company provided three-way splitter (5 Mhz -1003 Mhz) TV at each endpoint, modem at one. Works fine since the cable company put in new line.

My parents have been complaining about wifi dead spots in their roughly 3000 sq-ft home. The house is 70s-era construction, and the walls are plaster on "rock lath" / "button board" construction (it's ...