10508 questions

12508 answers


22026 members

0 votes
40 views 2 comments

I have set up an VPN Server on a RUT240. Now I want to connect another RUT240 Router as a client to this VPN network. I have followed the instructions according to this example: https://wiki.teltonika-networks.com/view/OpenVPN_configuration_examples

Because the router that functions as the VPN server has a mobile sim card and therefore no own public IPv4 address, I wanted to use its IPv6-address. So I entered the IPv6 address in the settings of the VPN client under "Remote host/IP address", but somehow my client does not want to connect to the VPN server.

Is it possible to use the IPv6 address for connecting to the VPN server? What could be the problem?

Thanks and greets,


1 Answer

0 votes

Hi Silvan,

Yes, you can use IPv6 in the “Remote host/IP address” section.

Select UDP protocol on both ends. Access the CLI and check the configuration with:

cat /etc/config/openvpn

Look for: option proto 'udp6' 

In case setting appears as option proto ‘udp’, open the file and edit it.

Note: To open a file with vi for editing. Press ‘i’, to enter INSERT mode, and start editing file. Press Esc to exit INSERT mode. Press ‘:x’ and 'Enter'. Changes will be saved.

Verify this on both ends, udp6 must be configured on client and server.

Kind Regards 

Anthony U.


Thanks a lot! I did this but now I receive the following error message:

Tue Jun 28 13:01:19 2022 daemon.err openvpn(Alfen_CL)[15956]: write UDP: Permission denied (code=13)

This error only shows up, when I use an IPv6 address.

Best regards,



Hi Silvan,

Can you share a Troubleshoot file via a private message?