I noticed that leaving the transmit power to 'driver default' results in the max power for a given channel being used. I got to wondering what a sane value is.
I tested values of 27 dBm all the way down to settings that simple would not register on my phone (iPhone 13) which I placed on a tripod a few rooms away from the AP.
iperf3 to test 3 streams uploading to the server for 30s. In summary, the speed measured didn't change despite reducing the power by >100x. Channel 149/80 Mhz width.
27 dBm (501 mW) 365 Mbit/s 22 dBm (158 mW) 341 Mbit/s 17 dBm (50 mW) 388 Mbit/s 12 dBm (15 mW) 348 Mbit/s 7 dBm (5 mW) 375 Mbit/s 6 dBm (3 mW) no connection
Given these results, what advantage does running at a huge value like 501 mW offer? What is a sane value to use?