@SleepWalker, sorry, I did not get your point with the first approach. The RockPi was connected to my laptop only and I’ve also disconnected the WIFI on the laptop. So the rockPi was absolutely not in contact with the existing opnSense instance.
So, you would like me to start the RockPi without the SD card?
BTW: I’m downloading the FreeBSD, and will also try that one.