Which version of the client are you using?
I would just like to remind you that there are two editions/versions of the openvpn client available on openvpn.net .
- the “official” version - OpenVPN Connect
- the Community Edition version
These editions, differ in the way they are configured.
Differences in configuration, have been a source of trouble, reported and explained on the IPFire forum.
Which version are you using?
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Below two helpful links:
https://community.openvpn.net/openvpn/wiki/OpenVPN-GUI-New
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A while ago, I downloaded the Community version of OpenVPN-2.5.8-I604-amd64.msi and installed it on Windows 11.
It made a tunnel with the remote IPFire without any problem.
I was able to open the remote IPFire configuration page by entering the IP address of green0 without any problems.