Thank you very much for your tip about the Ring Intercom, I didn’t know that. I’ll order one right away.
My neighbor managed to get the Videx 3171 working with the Opener, but with certain limitations. The handset must never go back to the intercom and hangs directly next to it. As soon as it rings, the intercom activates immediately, but the rest works. That was not an option for me. Unfortunately, I ordered the Opener and haven’t opened it since (still in its original packaging).
I personally find Nuki Support extremely poor, unfortunately again typical for a German-speaking company. I’m going to buy the Ring Intercom right now.