Sorry I'm not responding in German. I don't speak or read German, but I can tell that the issue you're experiencing is the same issue I had. Take a look at this article that I wrote. You'll need to flash the v4.0.23 BIOS on your APU4b4 in order for OPNsense 19.1 to work. The problem stems from a BIOS bug that is triggered in FreeBSD 11.2, but not in FreeBSD 11.1.If you have an existing OPNsense 18.7 installation, you will want to perform the following:1. Gain console access to your OPNsense installation2. Install the flashrom package: pkg install flashrom3. Download the BIOS firmware (this link is for the APU4): fetch http://pcengines.ch/file/apu4_v4.0.23.rom.tar.gz4. Untar the BIOS: tar -xf apu4_v4.0.23.rom.tar.gz5. Flash it: flashrom -p internal:boardmismatch=force -w apu4_v4.0.23.romNow you can go ahead with the OPNsense 19.1 upgrade (or installation).The article I wrote with more detailed instructions is: https://github.com/lattera/articles/blob/master/hardware/apu/2019-02-05_flashing_bios/article.md