Nucleo receiver

#include "mbed.h"
#include "lwip-interface/EthernetInterface.h"

DigitalOut led1(LED1);
DigitalOut led2(LED2);
DigitalOut led3(LED3);

static const char*          mbedIP       = "192.168.0.38";  //IP  
static const char*          mbedMask     = "255.255.255.0";  // Mask
static const char*          mbedGateway  = "192.168.0.3";    //Gateway

const int PORT = 50081;

EthernetInterface eth;

SocketAddress rd_addr;
UDPSocket rd_sock(&eth);

void receive()
{
   
     int bind = rd_sock.bind(PORT);

    char buffer[256];
    
    while(true){
    int ret = rd_sock.recvfrom(&rd_addr , buffer, sizeof(buffer));
    
    if(ret > 0){
    buffer[ret] = '\0';
    printf("Packet from \"%s\": %s\n", rd_addr.get_ip_address(), buffer);
    led3 = !led3;
    }

    else{
    printf("error %d\n", ret);
    led2=!led2;
    }
    }
    
}


int main() {

    Thread receiver;

    eth.set_network(mbedIP, mbedMask, mbedGateway);
    eth.connect();

    receiver.start(receive);

    while (true)
    {
        led1 = !led1;
        wait_ms(20);
    }
}