Hi  @colporteur,

It seems that you have referred to this thread to do troubleshooting.

Is the router's WAN IP a public IP? Refer to the following information for judgment:

1) Private IPv4 addresses have the following class configurations:

Class A IP addresses: from 10.0.0.0 to 10.255.255.255

Class B IP addresses: from 172.16.0.0 to 172.31.255.255

Class C IP addresses: from 192.168.0.0 to 192.168.255.255

2) Apart from the private IP addresses in the above 3 classes, there is another range of IP addresses, which looks like public IP address, but Carrier Grade NAT (CGNAT) address. They are from 100.64.0.0 to 100.127.255.255, which are usually not real public IP address either.

3) Or you could also google your public IP address on a client device connected to the Router, then compare it with the Router WAN IP address. If they are the same, it means the Router WAN IP is a real public IP address, if not, it means it is private IP address or the CGNAT address.

For OpenVPN, you could refer to this guide: How do I troubleshoot if the OpenVPN is not connecting

If the above steps still cannot solve the problem, please provide the following information for further troubleshooting:
1.    Model no., hardware and firmware version of your TP-Link router, model no. of the VPN client device
2.    Your specific network topology and what you want to achieve via VPN
3.    The current problem phenomenon
4.    The .ovpn file for OpenVPN, and screenshots of all VPN Settings
5.    Log file of the VPN client if you have

You can email support.forum@tp-link.com, attaching Forum ID 762126 and details, and we will have a dedicated person to assist in analysis and follow-up.