Docker VPN fails when Synology VPN is stopped 🤪

[Telos]

A few days ago I shutdown Synology's VPN server, as it was seldom used. However yesterday, when I launched the Docker container qbittorrentvpn, its web GUI failed.

After changing the containers VPN credentials (I use AirVPN), and updating the Docker image, I continued to get TUN errors whenever the container started.

2022-02-18 03:31:52	stdout	2022-02-18 03:31:52.441766 [info] OpenVPN config file (ovpn extension) is located at /config/openvpn/AirVPN_NO-Oslo_Camelopardalis_UDP-443.ovpn
2022-02-18 03:31:52	stdout	2022-02-18 03:31:52.377470 [info] VPN_ENABLED defined as 'yes'
2022-02-18 03:30:28	stdout	Fri Feb 18 03:30:28 2022 Exiting due to fatal error
2022-02-18 03:30:28	stdout	Fri Feb 18 03:30:28 2022 ERROR: Cannot open TUN/TAP dev /dev/net/tun: No such file or directory (errno=2)

After my frustration level subsided, I remembered exiting several packages a few days before, and for some random reason, I restarted Synology VPN server. When restarting the qbittorrentvpn container, the TUN errors ceased, and I was connected to the AirVPN server.

Hopefully this is obvious to some of you, but I don't understand why shutting down the Synology VPN Server (which accepts incoming connections), would affected a Docker container with an outbound connection to a VPN server.

As it seems now, the Synology VPN Server must be kept running for my container to function. Presumably, if I uninstall the VPN Server, my container is useless.

What is going on here? Why am I dependent upon the VPN Server for my Docker VPN connection? How can I break this dependency so that that container connects when the Synology VPN Server is not running (or uninstalled).

 

[Akira]

I had to set the following script to run at boot:

#!/bin/sh
 
# Create the necessary file structure for /dev/net/tun
if ( [ ! -c /dev/net/tun ] ); then
    if ( [ ! -d /dev/net ] ); then
        mkdir -m 755 /dev/net
    fi
    mknod /dev/net/tun c 10 200
fi
 
# Load the tun module if not already loaded
if ( !(lsmod | grep -q "^tun\s") ); then
    insmod /lib/modules/tun.ko
 
fi

It used to regularly happen to me with and without the synology VPN running.
I never managed to get the Synology one to run in a stable manner.

 

[Rusty]

As @Akira said you need to make a bootable script especially if you are on DSM7, but in 6 as well. Once you get dev/tun configured it will all work again.

 

[Telos]

As @Akira said you need to make a bootable script

Can this be done via Task Scheduler>Create/Triggered Task? Or?

 

[Rusty]

Yes it can be run even manually and you will not have to reboot the nas.

 

[Telos]

Super. Thanks!