I2C comunication, ESP->Nano on endTransmission no ACK fron nano
I'm a fool, I tried to detect other devices in the setup function before the Wire.begin(PIN_SDA, PIN_SCL,  I2C_MASTER);
I Found it only because of you. The rubber duck. I started to write the program down to post it here and bingo.
That was the reason why the master had the &quot;NACK&quot; answer. The master was not started yet.
Thank you