I currently lease my modem through my ISP-Cable One (2.5ghz). They only support Arris/Netgear modem/router combos. I live in a two-story home that is only 10 years old. The wifi does not work well on the second floor, even in the room directly above the modem/router. Would upgrading to a dual band modem/router help extend the wifi? Would an extender still be needed? Any suggestions would be helpful.