Larghezza di banda radio Ubiquiti

Put simply, WiFi speeds are inflated for marketing (since forever, this isn't UBNT trying to pull a fast one).

As WiFi is half-duplex, the "300mbit" is the sum of both Tx and Rx ... so the AP "over the air" connection in either direction is only 150 mbit max (vs. 100 mbit max in both directions simultaneously for 10/100 FDX of ethernet).

Now that we've got the OTA speed of 150 mbit, we also have to account for the WiFi protocol overhead, and CSMA delays, interference, etc. which brings the effective data rate down to about 80mbit.

In addition to that, you're almost never going to run a 2.4 GHz AP on HT40, as it takes 2/3 of the available non-overlapping channels, and means that you've increased your susceptability to interference. Here ("typical" suburban wifi soup), if I was to put my 2.4GHz radios* on HT40, I would see zero speed increase, due to all the people around me.