Of course, when you get to buildings that are old enough, you have several layers of solid material (brick/stone) on the exterior, as well as things like double

Of course, when you get to buildings that are old enough, you have several layers of solid material (brick/stone) on the exterior, as well as things like double-thickness brick interior walls as well. This doesn't do RF propagation any favors, either. My home was built in 1830 and 2.4Ghz wifi is strictly line of sight within the building, and cellular phones must be kept near windows on the side of the building facing the nearest cell tower to function. And this isn't in a rural area either, this is life in a brownstone in the middle of a large city...