Just as everybody got used to the idea that 802.11b sucked, 802.11g came along. Promising 54 screaming Mbps, 802.11g was still only half the speed of Fast Ethernet, but five times faster than original Ethernet! Right? Well, no. Just like 802.11b, the advertised speed was really the maximum physical layer data rate, not anything you could ever expect to see on a progress bar. And also like 802.11b, your best case scenario tended to be about a tenth of that—5 Mbps or so—and you’d be splitting that 5 Mbps or so among all the computers on the network, not getting it for each one of them like you would with a switched network.
802.11n was introduced to the consumer public around 2010, promising six hundred Mbps. Wow! Okay, so it’s not as fast as the gigabit wired Ethernet that just started getting affordable around the same time, but six times faster than wired Fast Ethernet, right? Once again, a reasonable real-life expectation was around a tenth of that. Maybe. On a good day. To a single device.
Read more at Ars Technica