Thanks for the effort. It’s a bit unfortunate that Stephane doesn’t chime in – that would make it a lot easier to figure out what his setup and mine have in common (at least it looks like its not only my Pi having this problem – of three known setups with Amp2+Pi4+max2play, it seems like two had problems). Did you try to email him?
You haven’t responded to my statement that my installation is out of the box, and the pi isn’t connected to the internet. In my book, that 100% rules out any issues with the home network or my router, as the pi4 doesn’t even know I have internet. If I’m missing something, please let me know.
As for the rest, I have followed the instructions on this site and used the recommended Win32Disk-Imager. If I should use a different SD card and different burning software or change other parameters, let me know and I will try that. For obvious reasons, the only thing I can’t provide is a second Pi.
Last but not least: In your test setup, was your Pi connected to the internet? Just to point out the obvious: The error sounds like max2play is trying to do something over internet, but can’t. So maybe the problem isn’t with the home network, but with the fact that there is no network to begin with. Thanks!