WiFi manufacturer put those alphabets to the model name to make customer easy to recognize up to which technology it supports, and most times put a number after that, such as N600, AC1300, AC1600, etc., to indicate what their maximum speed is.
Customers, like me, easily believe that N600, for example, would support 600 Mbps max speed for a connection between one device and the router theoretically. You probably have heard that this 600 Mbps is not a realistic, but still theoretically possible.
Wrong.
This number does not provide much information about the speed of 'a single connection'. It rather gives theoretical maximum speed that the router can support for 'all connections'.
For example, the maximum speed of a single connection in WD MyNet N600 is 300Mbps, not 600Mbps. They used N600 in the model name because the device can support up to 300 Mbps for 2.4Ghz and 5Ghz respectively. The maximum speed (more like throughput) of the router, 600Mbps, can be achieved when two devices are connected at 300Mbps on 2.4Ghz and 5Ghz respectively.
This is tricky and hard to be aware for a non-professionals, as many people would just believe that AC1900 would perform much better than N300 with their MacBook Air or Nexus 5.
In addition to the WiFi technology, like AC or N, there is another crucial part that determines the maximum WiFi speed of a device: the number of radios.
For the older 802.11 technologies, such as a/b/g, a device can only use a single radio. Therefore, the maximum speed was fixed to 54Mbps in 802.11g for example.
On the other hand, newer technologies including n and ac employ MIMO concept which can utilize multiple radios to achieve higher speed. (Note that this is a different concept from dual-band support like 2.4Ghz and 5Ghz). Only when both of your mobile device and WiFi router are equipped with multiple radios, you can get a higher speed. It totally depends on how many radios your mobile device is equipped with.
For example, if you connect your Nexus 5X (2x2 MIMO support) to a N600 (300 for 2.4GHz plus 300 for 5GHz, 2x2 antenna) router with 802.11n 5Ghz, the maximum speed can be up to 300 Mbps. However, if you connect the old Nexus 5 (no MIMO) to the same router, the maximum speed is only 150 Mbps, because 150 Mbps is the max speed at 1x1 radio of the Nexus 5. Nexus 5 supports 802.11ac though. If the Nexus 5 is connected to AC1300 router, for example, it can have at most 433 Mbps (Max speed of 802.11ac with 1x1 radio).
The table below shows the maximum speed of 802.11 standards at different radio settings.
| Radio configuration | 1x1 | 2x2 | 3x3 |
| 802.11ac 5GHz | 433 | 866 | 1300 |
| 802.11n 5GHz | 150 | 300 | 450 |
| 802.11n 2.4GHz | 72 | 144 |
Also, the radio configuration of a few well-known devices are presented.
| Device | Support mode | Radio conf | Max speed (ac) |
| Nexus 5 | n, ac | 1x1 | 433 |
| iPad Air, iPhone 6 | n, ac | 2x2 | 866 |
| Macbook Air | n, ac | 2x2 | 866 |
| Nexus 5X | n, ac | 2x2 | 866 |
At last, I should emphasize again that all these speeds are theoretical. In practice, it's not rare that 144Mbps speed at Macbook Air (connected with 802.11n, 2.4Ghz) is far quicker than 300Mbps-connected Nexus 5X. This is because laptops usually embed a big antenna compared to the smaller mobile devices. Also, laptops can have higher power range at WiFi chip-set which performs better.
For your information, this is a bench-marked network speed in reality. All devices are connected to N600 router which supports only 802.11n up to 300Mbps (2x2 config).
| Band | 2.4 (144/72) | 5 (300/150) |
| Macbook Air (2x2) | 103 | 113 |
| iPad (2x2) | 78 | 110 |
| Nexus5 (1x1) | 45 | 99 |
Although theoretical max-speed of Macbook and iPad, 300Mbps, is twice as the Nexus 5's max speed (150Mbps), the actual speed is almost same across all the three devices.
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