OpenVPN on internal IP?

[republicus]

Is it possible to run OpenVPN ontop of OPNsense for internal connections only?

I currently have OPNsense behind a modem/router and setup as the DMZ.

So far it has worked well except that I would like to allow clients on the router above to be able to connect to OPNsense via OpenVPN.

The OpenVPN server is setup authenticating ONLY with clients that are on a different external IP.

When changing the FQDN to the OPNsense WAN interface IP, every attempt fails to connect.

I do not see any traffic on OPNsense logs indicating why it has failed.

Any suggestions to make this work?
Thanks for your time!