RTL8401 (XID 240) was never supported by r8169. Having said that nothing was dropped from the driver. And most likely you don't have to compile r8101 yourself, most distro's have a pre-compiled package.
- Bug#956868: RTL810xE chipset not detected, network card u... Camaleón
- Bug#956868: RTL810xE chipset not detected, network c... Camaleón
- Bug#956868: Use Realtek's r8101 driver Heiner Kallweit
- Bug#956868: Use Realtek's r8101 driver Camaleón
- Bug#956868: Use Realtek's r8101 driver Heiner Kallweit
- Bug#956868: Use Realtek's r8101 driver Camaleón
- Bug#956868: Use Realtek's r8101 driver Heiner Kallweit
- Bug#956868: Use Realtek's r8101 driver Camaleón
- Bug#956868: Solved on Debian kernel 5.6.14-1 (RTL810x... Camaleón