It has already been asked how many clients can connect to an ESP32 AP, but the answer is far from clear; the best one is from a year and half ago (ESP32 AP max connections: 4 or 10?) :
The answer is as clear as any other EspressIf configuration data, it is 4 or maybe 5, or 8, or 12, 16 or even 20 (the same as a ESP8266!)
As I'm trying to move a project from the ESP8266 because it does not have enough AP connections, two questions can be asked :
what is the maximum number of AP connections supported by the 4.0 ESP-IDF framework ?
can it be increased in any way ?