poor wifi coverage and unstable internet speed

WiFi signal doesn’t do well with wall and stair, as they cann’t penetrate and have to reflect signal base on surrounding objects. It applies to many other routers on the market as well. If you want good signal, try to buy a wireless wifi repeater.

It really just depends on the signal strength of the router. I don’t think that the boost is the weakest thing out there, but I imagine it is not the strongest either. You want to look for a position to place routers that don’t have metal or concrete objects directly in the way, is elevated from the floor, and away from a wall by at least a foot. That gives you your best setup for the house, and for areas it cannot reach, you’ll need a repeater/range extender.