Synchronising ESP32 Modules Over Wifi

[microderm]

Hi, what is the best time synchronisation between two ESP32 modules I could reliably get using wifi (and how)?

I have acheived synchronisation to within about 3 us using Nordic nRF2401 transmitters with ESB protocol. With ESB, it it easy, as the transmission process is very predictable and always takes the same time to transmit and receive data. I would like to do similar work using ESP32, as I like the hardware.

I have experimented with ESP32 by connecting two modules by wired I/O to report when data arrives. Sending a small packet yields a range of transmission times from 1457 to 1580 us and sometimes up to 5170 us. It seems too variable to be useful. How could I get better results?

Any thoughts?