UDP广播不工作是为什么？

我正在尝试使用以下代码发送 UDP 广播：
代码：全选void write_UDP(uint8_t *buffer, int length)
{
   static struct espconn *myEspconn;
   unsigned long remote_ip;
   ip_addr_t ipaddr;

   ets_uart_printf("Sending UDP data!\r\n");

   myEspconn = (struct espconn *)os_malloc(sizeof(struct espconn));
   myEspconn->type = ESPCONN_UDP;
   myEspconn->state = ESPCONN_NONE;
   myEspconn->proto.udp = (esp_udp *)os_malloc(sizeof(esp_udp));
   myEspconn->proto.udp->local_port = UDP_BROADCAST_PORT;
   myEspconn->proto.udp->remote_port = UDP_BROADCAST_PORT;
   remote_ip = IPADDR_NONE;
   IP4_ADDR(&ipaddr, 255, 255, 255, 255);
   os_memcpy(myEspconn->proto.udp->remote_ip, &ipaddr.addr, 4);
   ets_uart_printf("ip addres: %x\r\n", ipaddr.addr);
   ets_uart_printf("ip addres: " IPSTR "\r\n", IP2STR(&ipaddr.addr));
    if (!espconn_send(myEspconn, buffer, length))
       ets_uart_printf("espconn_send error!\r\n");
    else
       ets_uart_printf("espconn_send succeeded!\r\n");
}

谁能帮我找出这里出了什么问题？