igmp_joingroup code... fails with a -6

gistfile1.txt

bool UDP_Multicast_init(void)
{
    //bool IGMP_joined;
    struct ip_addr ipgroup;
    struct udp_pcb *g_udppcb;
    char msg[] = "gaurav";
    struct pbuf* p;
    p = pbuf_alloc(PBUF_TRANSPORT,sizeof(msg),PBUF_RAM);
    memcpy (p->payload, msg, sizeof(msg));

    struct ip_info local_ip;

    const uint8_t mode = sdk_wifi_get_opmode();

    if (mode & STATION_MODE) {
      sdk_wifi_get_ip_info(STATION_IF, &local_ip);
    } else {
      sdk_wifi_get_ip_info(SOFTAP_IF, &local_ip);
    }
    
    //224.0.1.186
    //IP4_ADDR(&ipgroup, 238, 0, 0, 3 ); //MultiCasting Ipaddress.
    IP4_ADDR(&ipgroup, 224, 0, 1, 186 ); //MultiCasting Ipaddress.
    g_udppcb =( struct udp_pcb*) udp_new();
    udp_bind(g_udppcb, IP_ADDR_ANY, 5683); //to receive multicast
    udp_recv(g_udppcb, NET_UDP_rec,NULL);// (void *)0); //NET_UDP_rec is the callback function that will be called every time you receive multicast

#if LWIP_IGMP
    int iret = igmp_joingroup(&local_ip.ip,(struct ip_addr *)(&ipgroup));
    printf("ret of igmp_joingroup: %d \n\r",iret);
#endif


    udp_sendto(g_udppcb,p,&ipgroup,5683); //send a multicast packet
    return iret == 0;
}