Why is my Remarkable 2 web interface working on macOS but not Debian?

How can I debug the failing Remarkable 2 web interface at http://10.11.99.1/ of my Remarkable 2 on Debian? How do I solve the issue on my Debian?

I have got a Framework notebook with a Debian bookworm system. The last years synchronisation over USB (both USB to USB-C and USB-C to USB-C) was working. However, I had once a call to the service that seemed to be solved by switching the USB cable to connect the notebook and the Remarkable 2.

They also told me that it could help to restart the Remarkable or the Notebook or both if the web interface in Firefox is not working. However, today I did all of that, tried three different cables between Remarkable and Framework, but the web interface did not show up. However, every time I use a Mac (USB-C to USB-C) from work for the web interface, it works flawlessly.

How can I debug the failing communication? Are there any tips for better connection?