Package: linux-image-6.1.0-9-amd64 Version: 6.1.27-1 Currently, Debian tries to use the cdc_ncm driver with the RTL8156BG, which fails without useful error. (ifup says the interface doesn't exist, neither systemd nor dmesg log anything notable, ip addr reports a mac address.)
I think it's supposed to use the r8152 driver, but the magic strings to use it are missing, and firmware-realtek might not have the correct blob. Additional notes for this diagnostic journey can be found at https://community.frame.work/t/responded-debian-11-ethernet-expansion-card-doesnt-work-after-install/24482/8 Based on my exploration of the kernel.org repos, this might need to be fixed by Realtek itself.
