Hardware disconnects with specific code

[PeteKnight]

@mikje have you read this:
http://help.blynk.cc/getting-started-library-auth-token-code-examples/blynk-basics/keep-your-void-loop-clean

You already have a timer declared, but you’re only using it for one thing, which is to to send your device uptime to the app.

This is in effect a 250ms interval timer, but done in a less efficient way than BlynkTimer would do it,

@mikje

if (currentMillis - previousMillis1 >= interval1) {
  previousMillis1 = currentMillis;

  digitalWrite(C4051,1);
  digitalWrite(B4051,1);
  digitalWrite(A4051,1);
}

@mikje

If I add this code the Serial.println(currentMillis); in the loop

You need to be de-cluttering your void loop, not adding to it

@mikje

nano with esp01

You need something with a lot more processing power and much higher clock speed in my opinion.

Pete.