// send an NTP request and wait for the result:
// Thanks to Michael Margolis for the original inspiration and RFC 5905 for the details. 
unsigned long getTime() {
  WiFiUDP Udp;
  Udp.begin(localPort);
  // NTP timestamp packet is 48 bytes:
  const int NTP_PACKET_SIZE = 48;
  // diff between NTP result and current UTC epoch is 70 years in seconds:
  const unsigned long SEVENTY_YEARS = 2208988800UL;
  // byte buffer for NTP packet:
  byte packetBuffer[NTP_PACKET_SIZE];
  // set all bytes in the buffer to 0
  memset(packetBuffer, 0, NTP_PACKET_SIZE);
  // simplest NTP request needs only the leap indicator, NTP version, and mode.
  // see RFC5905: https://datatracker.ietf.org/doc/html/rfc5905
  packetBuffer[0] = 0b00100011;  // Leap indicator 0, version 4, mode 3
                                 // send request to pool.ntp.org, port 123:

  Udp.beginPacket("pool.ntp.org", 123);
  Udp.write(packetBuffer, NTP_PACKET_SIZE);
  Udp.endPacket();
  // wait for return packet:
  while (!Udp.parsePacket())
    ;
  // Parse the return packet:
  Udp.read(packetBuffer, NTP_PACKET_SIZE);
  //the timestamp  (32 bit integer) starts at byte 40
  // of the received packet:
  unsigned long result = 0;
  for (byte b = 40; b < 44; b++) {
    // shift the whole thing over 8 bits, and add the next byte:
    result = (result << 8) | packetBuffer[b];
  }
  // subtract the time since 1900:
  result = result - SEVENTY_YEARS;
  return result;
}

  configTime(gmtOffset_sec, daylightOffset_sec, "pool.ntp.org");
  time_t now = time(nullptr);
  while (now < SECS_YR_2000) {
    delay(100);
    now = time(nullptr);
  }