VPN over RUTX12

I set up a VPN over RUTX12 using this guide.
I Connected a Windows11 machine to the network using a vpn client, and a Ubuntu22.04 machine via LAN (Ethernet cable).
SSH remote from the vpn-client to the LAN machine was successful.

When I try to communicate between the two machines i.e. run a simple python code using TCP/IP - I have no response.

*Turning off Windows firewall did not help.
*The OpenVPN is configured to use UDP (as suggested in the guide). Does it make a difference?

The main issue is that I don’t really know what it is…
How can I solve/workaround this case?

Thanks in advance!


Since you can SSH over the OpenVPN without issues, the connection is there. The UDP should not be an issue since the packets are encapsulated.

What firmware do you have installed?

Hows the overall internet connectivity on RUTX12? Are there any issues?

It is likely that the issue is related to the firewall or other network settings on one of the end devices.

Could you install tcpdump from the command line (SSH) and run it on your OpenVPN interface?:

opkg update
opkg install tcpdump

find you OpenVPN interface via:


And run tcpdump on OpenVPN interface (replace tun_openvpn):

tcpdump -i tun_openvpn

Then, run your python script. Do you see any packets coming in?

Command line instructions are available here. Make sure you use ‘root’ as the username. The password will be the same password that you use to access the WebUI.

Kind Regards,

Thanks for the answer.
I signed in to root in at the CLI of the webUI. When tried to update I got “Failed to download the package list”. Can you please instruct with more details? I’m probably not so familiar with this field.
The firmware is 7.04.5. Connectivity is fine.


It is okay if 1 or 2 repositories fail to update. As long as you are able to install the tcpdump package, this is not an issue.
One more thing to check, would be to lower the MTU on the mobile interface. This can be done by navigating to Network → Interfaces → General, editing the mob1s1a1 interface (SIM1), and in the advanced settings changing the Override MTU option to 1300. The same can be done for mob2s1a1 (SIM2). Let me know if this helps!

Best regards,

This topic was automatically closed after 15 days. New replies are no longer allowed.