W5500 + udp

небольшой код, из примера библиотеки w5500.h, приведенный ниже, не получает пакеты.
какие есть варианты?

Код (C++):

#include <SPI.h>        
#include <Ethernet_W5500.h>
#include <EthernetUDP.h>

// Enter a MAC address for your controller below.
// Newer Ethernet shields have a MAC address printed on a sticker on the shield
#if defined(WIZ550io_WITH_MACADDRESS) // Use assigned MAC address of WIZ550io
;
#else
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
#endif

unsigned int localPort = 8888;      // local port to listen for UDP packets

IPAddress timeServer(132, 163, 4, 101); // time-a.timefreq.bldrdoc.gov NTP server
// IPAddress timeServer(132, 163, 4, 102); // time-b.timefreq.bldrdoc.gov NTP server
// IPAddress timeServer(132, 163, 4, 103); // time-c.timefreq.bldrdoc.gov NTP server

const int NTP_PACKET_SIZE= 48; // NTP time stamp is in the first 48 bytes of the message

byte packetBuffer[ NTP_PACKET_SIZE]; //buffer to hold incoming and outgoing packets

// A UDP instance to let us send and receive packets over UDP
EthernetUDP Udp;

unsigned long sendNTPpacket(IPAddress&); // prototype

void setup()
{
// Open serial communications and wait for port to open:
  Serial.begin(9600);
   while (!Serial) {
    ; // wait for serial port to connect. Needed for Leonardo only
  }


  // start Ethernet and UDP
#if defined(WIZ550io_WITH_MACADDRESS)
  if (Ethernet.begin() == 0) {
#else
  if (Ethernet.begin(mac) == 0) {
#endif
    Serial.println("Failed to configure Ethernet using DHCP");
    // no point in carrying on, so do nothing forevermore:
    for(;;)
      ;
  }
  Udp.begin(localPort);
}

void loop()
{
  sendNTPpacket(timeServer); // send an NTP packet to a time server

    // wait to see if a reply is available
  delay(1000);
  if ( Udp.parsePacket() ) {
}
}