The Asus RT-N56U is a Dual-band 2.4 GHz and 5 GHz Wi-Fi Router/Access Point.
A Wi-Fi band is the same as the frequency. So there are 2 bands with the Asus RT-N56U. 2 GHz and 5 GHz (more formally written as 2.4 GHz and 5 GHz).
2 GHz Band
- Range and coverage. As 2 GHz is lower than 5 GHz in the radio spectrum, it's attenuated (blocked) less by things like walls, ceilings and other obstructions. Therefore 2 GHz signals will travel further into your home. You will still find the speed drops off with distance away however.
Not as good as 5 GHz:
- Raw speed and performance when close to the router. 5 GHz opens up more spectrum for less interference than 2 GHz. 2 GHz also operates at half the bandwidth (20 MHz) compared to 5 GHz (40 MHz), so Wi-Fi speeds (theretical) will be half as good.
5 GHz Band
- Performance as there is less interference and more channels available with 5 GHz compared to 2 GHz
- Performance as with 5 GHz, you can operate a 40 MHz bandwidth which is enabled by default with the Asus RT-N56U. With 2 GHz, the default bandwidth is set to 20 MHz. So you will get 2x the speed (theoretical) with 5 GHz.
Not as good as 2 GHz:
- Wi-Fi Range/Coverage as the 5 GHz signals are attenuated (blocked) more easily than the 2 GHz signals.
- Compatibility with all your Wi-Fi devices. 5 GHz is relatively new compared to 2 GHz, therefore some of your older devices may not work with 5 GHz.