Thanks for the valuable info, boarchuz. I agree that it’s generally not worth it to improve the internal RTC except by manually calculating the average frequency between two time synchronizations. The oscillator’s characteristics are just too unfavorable to compensate well – the temperature coeffici...

Right, if you control the AP, you can simplify option 1. Set the ESP to promiscuous mode, wait until the beacon arrives (102.4ms max) and read wifi_pkt_rx_ctrl_t's timestamp, which should correspond to the field in the beacon frame (uptime in microseconds). While this gives only relative time, you c...

A couple of months ago, I made a short video about this (https://www.youtube.com/watch?v=fZAR8WTKiSg). I tested it on ESP32-S3, but it should be valid for the ESP32-C3 as well. As you noted, too, the clock drift is strongly temperature-dependent. This is compounded by the fact that the internal osci...