I have installed Ubuntu 20.4 on a new build with the MSI Z490 motherboard but the wired ethernet is not working. The ubuntu distro minimal so installing the driver from Realtec fails because the tools are not available. I would be grateful for any useful advice. Here are some diagnostics which might help.

>>>>>>>>>>>>>>>:~$ lspci -nnk | grep -ia3 net
Subsystem: Micro-Star International Co., Ltd. [MSI] GK208 HDMI/DP Audio Controller [1462:8c93]
Kernel driver in use: snd_hda_intel
Kernel modules: snd_hda_intel
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 [1462:7c75]
Kernel modules: r8169

>>>>>>>>>>>>>>>:~$ cat /etc/network/interfaces
/etc/network/interfaces: No such file or directory

>>>>>>>>>>>>>>>:~$ ls /lib/modules/5.4.0-42-generic/kernel/drivers/net/ethernet/realtek/
8139cp.ko 8139too.ko atp.ko r8169.ko

>>>>>>>>>>>>>>>:~$ ls /lib/modules/5.4.0-42-generic/kernel/drivers/net/ethernet/realtek/r8169.ko
/lib/modules/5.4.0-42-generic/kernel/drivers/net/ethernet/realtek/r8169.ko
>>>>>>>>>>>>>>>:~$

>>>>>>>>>>>>>>>:~$ cat /etc/modules-load.d/modules.conf
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with "#" are ignored.

>>>>>>>>>>>>>>>:~$ lsmod | grep 8169
r8169 90112 0

>>>>>>>>>>>>>>:~$ sudo lshw -C network
*-network UNCLAIMED
description: Ethernet controller
product: RTL8125 2.5GbE Controller
vendor: Realtek Semiconductor Co., Ltd.
physical id: 0
bus info: pci@0000:03:00.0
version: 04
width: 64 bits
clock: 33MHz
capabilities: pm msi pciexpress msix vpd cap_list
configuration: latency=0
resources: ioport:3000(size=256) memory:ab200000-ab20ffff memory:ab210000-ab213fff

>>>>>> System settings shows only NVIDIA drivers.

What does show?

1 members found this post helpful.

Thanks for the quick response.
.
zzzzzzzzzzzzzzz:~$ ip link show
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

Try downloading (from another computer) the driver from the Realtek website and installing per the instructions.

https://www.realtek.com/en/component...press-software

You might need to blacklist the r8169 module.

Thank you for responding michaelk. The problem I have with installing the Realtec drivers is that I can't install gcc because it's dependencies are not on the Kubuntu 20.4 installation disk. Do you know of a work round for this?

From what I can see, gcc is included onto Kubuntu 20.04.1 installation disc. Try to install the package build-essential. It should pull gcc, make, and other tools needed to build something from source.

1 members found this post helpful.

Build Essential could not be marked for installation - "Depends: build-essential, but is not installable"
However Ubuntu 19.10 installs, and the Realtec package works on it, so I will upgrade from this.
Thanks to all contributors. Since there isn't a "bodged around it" option will close this thread as "solved".

I had a very similar problem. A fresh install of Ubuntu Desktop 20.04 LTS had no network connection despite being plugged into a known good ethernet network (the windows side worked fine, and so did an installation of Ubuntu 21.x). I googled my way to needing to install the realtek drivers, however, this was impossible because the realtek installation required compilers and "make", and my system did not have these, and for obvious reasons I could not download them.

Here's what I did: I created a virtualbox installation from windows of the same version of Ubuntu, then ran:

mkdir build-deps
cd build-deps
apt download $(apt-cache depends --recurse --no-recommends --no-suggests --no-conflicts --no-breaks --no-replaces --no-enhances build-essential | grep "^\w" | sort -u)
cd ..
tar cvf build-deps.tar build-deps
gzip build-deps.tar

I then copied this tarfile onto a usb stick, transferred it to the marooned machine, and did

tar xzvf build-deps.tar.gz
cd build-deps
dpkg -i *.deb

and all of the necessary prerequisites were installed. Then it became possible to install the realtek drivers using their autorun.sh.

Another path in this situation is to buy a USB to ethernet adapter, and use that to get connectivity to get everything fixed up, but I did not want to wait for that.