ESP_igrr wrote:This looks like the chip browning out when doing RF calibration, which drains a lot of current. Please try connecting a power supply capable at least of 500mA.

Jackpot ! I've changed the source to 18650 Li-ion and works like a charm Thank You for helping

Hello ;) I have problems with using Wi-Fi. I've uploaded this sketch Wifi-scan (basic sketch from Arduino libraries) #include "WiFi.h" void setup() { Serial.begin(115200); // Set WiFi to station mode and disconnect from an AP if it was previously connected WiFi.mode(WIFI_STA); WiFi.disconnect(); del...