Working with USB powered from computer, but not from USB Power Adapter

[ermo042]

I have a rather simple sketch, that connects WiFi and MQTT, sends a topic across and goes to sleep.
When powered with an USB cable from the computer, all works fine and the MQTT message is received right after plugging in (also of course the serial monitor works fine).

However, when I connect the ESP32 via a Wall Adapter (taken from AWS FireTV Stick, so it has sufficient current rating) - the MQTT message is never going through.

The only thing I see is that the PowerLED on the ESP32 device is on. And a ESP8266 plugged into the same line works without issues.
I even have no great idea to debug this behavior - obviously I cannot use the Serial Monitor - )
I suspect is is the WiFI Connection, but could also be MQTT ... but WHY ??

Do you have any ideas ?

[derekg]

did you ever find out what caused this? I'm having the same issue with a Xiao ESP32C3.

[derekg]

never mind. it's because of while(!Serial)