Wifi also works at 2.4ghz.
Discussion
I haven't used wifi for years.
The falloff rate of the power envelope is very localized to the receiving device. IE, the phone or laptop draws and attenuates the signal strength TO the device.
I'm way happier using ethernet anyway, it's much faster. Never liked wireless. Tried to get into it for years, but never found it reliable for moving large files around, and so on.