RTL8125B Ethernet help

[cjlorenz81]

Good evening everyone. I've run into an aggravating issue here. I have a somewhat new PC build and ran into the fact that my ethernet does not work in Kali.
System Specs:
Motherboard: MSI MPG Z490 Gaming Carbon WiFi
CPU: Intel Core i5 10400
RAM: Corsair DDR 4 Vengeance Pro 16GB

My WiFi adapter works fine out of the box so to speak. In fact even my USB-C NIC works, but I'd rather use the on-board NIC. I did some research on this matter, and according to MSI it's an Realtek 8125B 2.5 GBe
So naturally I thought maybe the drivers weren't installed for this, so I attempted to download and install them from realtek, but kept getting make clean errors. Then I did some poking around in the /lib/firmware/rtl_nic directory and found that I do have the rtl8125B.fw and other firmwares there.

I know you'll need these details as well.

wolf@Wolf-DT:/lib/firmware/rtl_nic$ lspci -knn | grep Eth -A2
	DeviceName: Onboard - Ethernet
	Subsystem: Intel Corporation Wi-Fi 6 AX201 160MHz [8086:0074]
	Kernel driver in use: iwlwifi
--
03:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller [10ec:8125] (rev 04)
	Subsystem: Micro-Star International Co., Ltd. [MSI] RTL8125 2.5GbE Controller [1462:7c73]
	Kernel modules: r8169

OS: Kali GNU/Linux Rolling x86_64 
Host: MS-7C73 1.0 
Kernel: 5.8.0-kali2-amd64 
Uptime: 25 mins 
Packages: 2667 (dpkg) 
Shell: bash 5.0.18 
Resolution: 1920x1080 
DE: Xfce 4.14 
WM: Xfwm4 
WM Theme: Kali-Dark 
Theme: Kali-Dark [GTK2/3] 
Icons: Flat-Remix-Blue-Dark [GTK2/3] 
Terminal: terminator 
CPU: Intel i5-10400 (12) @ 4.300GHz 
GPU: AMD ATI Radeon RX 470/480/570/570X/580/580X/590 
Memory: 1262MiB / 15934MiB

I'm out of ideas of what I need to do to get this working. Any and all help would be greatly appreciated.

[MateMalice]

Hi cjlorenz81,

I have only managed to get this network card working by using the official manufacturer's drivers, which can be found here:
https://www.realtek.com/en/component...press-software

See the 2.5 Gbit Ethernet drivers for Linux - version 9.003.05 dated 2020/05/25. It says it supports up to kernel 5.6, but I have managed to get it working on kernel 5.8. It will ask for an email address and a captcha before it lets you download the files, but these are the only ones I have managed to get working. Once you've downloaded the files, you might want to use lsmod and modprobe to remove any r8xxx or realtek kernel modules that might conflict. Then extract the downloaded archive and run ./autorun.sh in a root terminal. This should compile and load the drivers - for me, the network adapter showed up straight away. You might need to run ifconfig eth0 up (or whatever the interface is called - you can list them using ifconfig -a).

Good luck! :-)