pfSense

Did you try the suggested fix on the ticket you linked? Put this in your advanced server config box:

push block-outside-dns

We could add that to the exporter, either in all cases or as another checkbox option.

I tried

push block-outside-dns pfSense & *setenv opt block-outside-dns* openVPN-Client

nslookup still tries to connect to local dns and gets a timed out. Maybe i missunderstood the ticket.

Modifying the metric of the local connection to a higher value than the vpn connection solves the problem but this isnt a good solution i think.

All we could do is push the setting or add it to the config. Beyond that it's a Windows problem that isn't anything we can help.

I haven't tested this either way, but according to the ticket you should be able to push that so long as your client is running a current version of OpenVPN. Try uninstalling the OpenVPN client and then installing the latest version either from the export package or from the OpenVPN community downloads. Then try the test again. Pushing the option should be enough, you don't need to use the setenv bit unless you want to control it in the client directly and not push it from the server.

I use mullvad vpn on one of my PCs which is running windows 10. As long as you are using openvpn 2.3.9 or newer, it has the block-outside-dns feature, which uses WFP. It definitely works. If you invoke this feature, you should not experience dns leakage.