1 and 2.4GHz are widely used. At present, the mainstream wireless AP, such as personal Fengrunda wireless AP, is basically like this. The wavelength of the signal is relatively long, which can be covered when it is blocked by multiple walls to ensure a certain signal strength.
The wavelength frequency of 2.5GHz wireless AP is higher, that is, the wavelength is slightly shorter, which leads to the penetration force is much weaker than that of 2.4GHz, so it will be more difficult to cover with a single transmission point of 5 GHz. Moreover, the cost is higher than that of 2.4GHz band equipment, and the current usage is not large.
3, 2.4GHz and 5GHz also have disadvantages. 2.4GHz is more susceptible to interference, while 5GHz has stronger anti-interference ability, so each has its own advantages and disadvantages, and it doesn't matter whether it is good or bad, so it can be used together.