OpenVPN Server configuration Instance (new)

[RES217AIII]

Hello forum,
I need help configuring an OpenVPN server in 23.7, new instances.
While everything ran smoothly and stable in 23.1.11 with the legacy configuration, I am unable to get a VPN server to run in the new instances.
In fact, after the upgrade to 23.7.1, the "old, legacy" servers can no longer be reached.
In perspective, I would like to transfer all VPN servers to the new instances and switch off the old servers.

Does one of the experienced users have the time and desire to show an inexperienced, enthusiastic OPNsense user which settings are necessary in the sense of a configuration guide?
What, if anything, do I have to enter in Bind if I use dynDNS, etc.?

Cheers  ;)
Bernd