[solved] Serial.readStringUntil does not work correctly in my code

[J-M-L]

why are you reading the Serial input 3 times?

@palhares

    timeLed_Green_Serial = Serial.readStringUntil('\n');
    timeLed_Yellow_Serial = Serial.readStringUntil('\n');
    timeLed_Red_Serial = Serial.readStringUntil('\n');

read only once and then test against the 3 possible cases.

we would advise against Serial.readStringUntil() and would suggest to study Serial Input Basics to understand how to deal with Serial input