NRF connect project.
SDL v2.5.1
Board: NRF5340
the application is running on it. the code support multiple connection to a pereferal.
Every thing is running properlly. But still only one phone can connect to the pereferal. The other phone only connects when the older one is dissconnected.
I am not understanding where can be the issue.

`proj.conf

`CONFIG_BT=y
CONFIG_BT_DEBUG_LOG=y
CONFIG_BT_SMP=y
CONFIG_BT_PERIPHERAL=y
CONFIG_BT_DIS=y
CONFIG_BT_DIS_PNP=n
CONFIG_BT_BAS=y
CONFIG_BT_HRS=y
CONFIG_BT_DEVICE_NAME="Zephyr Heartrate Sensor"
CONFIG_BT_DEVICE_APPEARANCE=833
CONFIG_BT_MAX_CONN=2``

main.c

/* main.c - Application main entry point */

/*
 * Copyright (c) 2015-2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/types.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <sys/printk.h>
#include <sys/byteorder.h>
#include <zephyr.h>

#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/conn.h>
#include <bluetooth/uuid.h>
#include <bluetooth/gatt.h>
#include <bluetooth/services/bas.h>
#include <bluetooth/services/hrs.h>

#define NUM_CONN_MAX    CONFIG_BT_MAX_CONN

static struct bt_conn *curr_conn[NUM_CONN_MAX];

static const struct bt_data ad[] = {
    BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR)),
    BT_DATA_BYTES(BT_DATA_UUID16_ALL,
              BT_UUID_16_ENCODE(BT_UUID_HRS_VAL),
              BT_UUID_16_ENCODE(BT_UUID_BAS_VAL),
              BT_UUID_16_ENCODE(BT_UUID_DIS_VAL))
};

static struct bt_conn **find_curr_conn(struct bt_conn *conn)
{
    int i;
    struct bt_conn **conn_found = NULL;

    for (i = 0; i < NUM_CONN_MAX; i++) {
        if (curr_conn[i] == conn) {
            conn_found = curr_conn + i;
            break;
        }
    }

    return conn_found;
}

static void connected(struct bt_conn *conn, uint8_t err)
{
    struct bt_conn **conn_room;

    if (err) {
        printk("Connection failed (err 0x%02x)n", err);
    } else {
        conn_room = find_curr_conn(NULL);
        if (conn_room) {
            *conn_room = bt_conn_ref(conn);
            printk("Connectedn");
        } else {
            printk("No room to trace connection!n");
        }
    }
}

static void disconnected(struct bt_conn *conn, uint8_t reason)
{
    struct bt_conn **conn_found;

    printk("Disconnected (reason 0x%02x)n", reason);

    conn_found = find_curr_conn(conn);
    if (conn_found) {
        bt_conn_unref(*conn_found);
        *conn_found = NULL;
    }
}

static struct bt_conn_cb conn_callbacks = {
    .connected = connected,
    .disconnected = disconnected,
};

static void bt_ready(void)
{
    int err;

    printk("Bluetooth initializedn");

    err = bt_le_adv_start(BT_LE_ADV_CONN_NAME, ad, ARRAY_SIZE(ad), NULL, 0);
    if (err) {
        printk("Advertising failed to start (err %d)n", err);
        return;
    }

    printk("Advertising successfully startedn");
}

static void auth_cancel(struct bt_conn *conn)
{
    char addr[BT_ADDR_LE_STR_LEN];

    bt_addr_le_to_str(bt_conn_get_dst(conn), addr, sizeof(addr));

    printk("Pairing cancelled: %sn", addr);
}

static struct bt_conn_auth_cb auth_cb_display = {
    .cancel = auth_cancel,
};

static void bas_notify(void)
{
    uint8_t battery_level = bt_bas_get_battery_level();

    battery_level--;

    if (!battery_level) {
        battery_level = 100U;
    }

    bt_bas_set_battery_level(battery_level);
}

static void hrs_notify(void)
{
    static uint8_t heartrate = 90U;

    /* Heartrate measurements simulation */
    heartrate++;
    if (heartrate == 160U) {
        heartrate = 90U;
    }

    bt_hrs_notify(heartrate);
}

void main(void)
{
    int err;

    err = bt_enable(NULL);
    if (err) {
        printk("Bluetooth init failed (err %d)n", err);
        return;
    }

    bt_ready();

    bt_conn_cb_register(&conn_callbacks);
    bt_conn_auth_cb_register(&auth_cb_display);

    /* Implement notification. At the moment there is no suitable way
     * of starting delayed work so we do it here
     */
    while (1) {
        k_sleep(K_SECONDS(1));

        /* Heartrate measurements simulation */
        hrs_notify();

        /* Battery level simulation */
        bas_notify();
    }
}

I tried many working samples but always one device connects.