How to correctly read data from FIFO on HPS and send it out through HPS Ethernet

I changed the FIFO to a dual port FIFO, and then used the same code to read the data in the FIFO. Everything looked normal. But when I added the function to send data, the reading of the data seemed to run counter to the correct result.

FIFO has a depth of 2048 and a width of 32. qsys2reading datasending data

/*   code for sending data    */
#include <stdio.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <stdint.h>
#include <unistd.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>

#define HW_REGS_BASE (0xC0000000)
#define HW_REGS_SPAN (0x04000000)
#define ALT_H2F_OFST  (0xFF500000)
#define HW_REGS_MASK (HW_REGS_SPAN - 1)
#define LED_PIO_OFFSET (0x00000408)
#define DEST_IP_ADDR "192.168.0.11"
#define DEST_PORT 1234

int main()
{
    int fd;
    void *h2f_axi_base;
    void *led_pio_addr;
    int sock;
    struct sockaddr_in dest_addr;

    fd = open("/dev/mem", O_RDWR | O_SYNC);
    if (fd == -1) {
        perror("could not open /dev/mem\n");
        return 1;
    }

    h2f_axi_base = mmap(NULL, HW_REGS_SPAN, PROT_READ | PROT_WRITE, MAP_SHARED, fd, HW_REGS_BASE);
    if (h2f_axi_base == MAP_FAILED) {
        perror("could not mirror the H2F AXI address\n");
        close(fd);
        return 1;
    }

    led_pio_addr = h2f_axi_base + ((unsigned long)(ALT_H2F_OFST + LED_PIO_OFFSET) & (unsigned long)(HW_REGS_MASK));

    sock = socket(AF_INET, SOCK_DGRAM, 0);
    if (sock == -1) {
        perror("socket creation failed\n");
        munmap(h2f_axi_base, HW_REGS_SPAN);
        close(fd);
        return 1;
    }

    memset(&dest_addr, 0, sizeof(dest_addr));
    dest_addr.sin_family = AF_INET;
    dest_addr.sin_port = htons(DEST_PORT);
    if (inet_pton(AF_INET, DEST_IP_ADDR, &(dest_addr.sin_addr)) <= 0) {
        perror("inet_pton failed\n");
        munmap(h2f_axi_base, HW_REGS_SPAN);
        close(sock);
        close(fd);
        return 1;
    }

    while (1) {

        uint32_t data = *((volatile uint32_t *)led_pio_addr);

        if (sendto(sock, &data, sizeof(data), 0, (struct sockaddr *)&dest_addr, sizeof(dest_addr)) == -1) {
            perror("sendto failed\n");
            break;
        }

    }

    close(sock);

    munmap(h2f_axi_base, HW_REGS_SPAN);
    close(fd);

    return 0;
}