Device or resource busy

Installing and Using OpenWrt Network and Wireless Configuration
1

Hello
I'm trying to install sing-box using this instruction

but I encountered an error:

> root@OpenWrt:~# sing-box check -c /etc/sing-box/config.json
> root@OpenWrt:~# sing-box run -c /etc/sing-box/config.json
> FATAL[0000] start service: initialize inbound/tun[tun-in]: configure tun interface: device or resource busy
> root@OpenWrt:~#

Please tell me how to overcome this error.

2

Your guide deals with immortalwrt

Can you provide output of

ubus call system board
3 
root@OpenWrt:~# ubus call system board
{
        "kernel": "5.15.137",
        "hostname": "OpenWrt",
        "system": "MediaTek MT7621 ver:1 eco:3",
        "model": "ASUS RT-AX53U",
        "board_name": "asus,rt-ax53u",
        "rootfs_type": "squashfs",
        "release": {
                "distribution": "OpenWrt",
                "version": "23.05.2",
                "revision": "r23630-842932a63d",
                "target": "ramips/mt7621",
                "description": "OpenWrt 23.05.2 r23630-842932a63d"
4

Are you using OpenWRT sing-box package? Uninstall immortalwrt package, delete all config, then install from package manager.
Will not hurt upgrading to 23.05.5 (using luci-app-attendedsysupgrade if you dont like command lines)

5

Initially I had openwrt 23.05.5 when I couldn't install sing-box I rolled back to openwrt 23.05.2
Yes, I use the sing-box package
I don't have the immortalwrt package installed
I install sibg-box on a completely clean system.

opkg install sing-box kmod-inet-diag kmod-netlink-diag kmod-tun iptables-nft.

To configure I use the commands:

echo "Setting sing-box"
uci set sing-box.main.enabled='1'
uci set sing-box.main.user='root'
uci commit sing-box

echo "Installing the TUN1 interface"
uci set network.sign_box='interface'
uci set network.sign_box.proto='none'
uci set network.sign_box.device='tun1'
uci set network.sign_box.defaultroute='0'
uci set network.sign_box.delegate='0'
uci set network.tun1.auto='1'
uci commit network

echo "Installing a Firewall"
section_name=$(uci add firewall zone)
uci set firewall.${section_name}.name='sing_box'
uci set firewall.${section_name}.input='ACCEPT'
uci set firewall.${section_name}.output='ACCEPT'
uci set firewall.${section_name}.forward='ACCEPT'
uci set firewall.${section_name}.masq='1'
uci add_list firewall.${section_name}.network='tun1'

echo "Installing a Firewall Forwarding"
section_name=$(uci add firewall forwarding)
uci set firewall.${section_name}.src='lan'
uci set firewall.${section_name}.dest='sign_box'
uci commit firewall