ESP8266 deepsleep not working properly after 1 hour

Question

I report a strange behaviour on deepsleep mangemnt: I have an esp8266 NodeMCU AMICA V2 board, if i put in deepsleep for 1800 seconds its fine and wake up as expected, then if I put in deepsleep for 3600 seconds it wont wakeup, i dont understand why since the code is still the same. To put on deepsleep i use this function: (in setup i also have added "pinMode(D0, WAKEUP_PULLUP);" but nothing is changed):

sleepSeconds = 3600;           
  Serial.println(sleepSeconds);
          digitalWrite(power, LOW);
            delay(250);
                ESP.deepSleep (sleepSeconds * 1000000);
             delay(2000);

I also tested the max deepsleep time with below function and resulting on 13591117817us, that is almost 226 minutes so it should not a problem:

  String result = "";
  uint8_t base = 10;

  do {
    char c = input % base;
    input /= base;

    if (c < 10)
      c +='0';
    else
      c += 'A' - 10;
    result = c + result;
  } while (input);
  return result;
}