Ubuntu 20.04 Server Not Recognising Ethernet Connection

Question

I have an ubuntu 20.04 server. When installing I connected an ethernet cable to the motherboard ethernet port. I am certain that it is connected to the internet but it won't connect.

I have tried troubleshooting:

$ lspci | grep -i eth yields:

02:00.0 Ethernet controller: Realtek Semiconductor Co., RTL8125 2.5GbE Controller (rev 04)

$ sudo lshw -c network yields:

*-network UNCLAIMED
    description: Ethernet controller
    product: RTL8125 2.5GbE Controller
    vendor: Realtek Semiconductor Co., Ltd.
    physical id: 0
    bus info: pci@0000:02:00.0
    version: 04
    width: 64 bits
    clock: 33MHz
    capabilities: pm msi pciexpress msix vpd cap_list
    configuration: latency=0
    resources: ioport:3000(size=256) memory:a1100000-a110ffff memory:a1110000-a1113fff

My /etc/network/interfaces:

# The loopback network interface
auto lo
iface eth0 lo inet loopback

# The primary network interface
iface eth0 inet dhcp

/etc/netplan/01-netcfg.yaml:

# This is the network config written by 'subiquity'
network:
  version: 2
  renderer: networkd
  ethernets:
    ens33:
      dhcp4: true

I have tried several options (this and that) but neither work for me. Am I missing something?

Answer 1

Allright, so as pointed out by @Silbee, the kernel did not support my ethernet adapter. So I figured I should write a step by step guide for others experiencing the same problems as I did.

Step 1: (Download kernel files)

I downloaded the following files in order to upgrade the kernel:

Then move to a USB drive (remember, we don't have the convenience of internet to do everything for us...)

example folder structure: D:/kernel/

You should have 4 files in the kernel folder on your usb drive.

Step 2: (Mount USB)

Create a folder for mounting your USB: $ mkdir /media/usb
Find USB drive address: $ lsblk
Mount USB drive in folder: sudo mount /dev/sdb1 /media/usb (my USB drive's address was sdb1)

Step 3: (Install new kernel)

To install:

Move to the kernel folder

$ cd /media/usb/kernel

And install the new kernel:

$ sudo dpkg -i *.deb

Step 4: (find ethernet interface)

If all has gone well as it did for me you should find a new interface when running the following command: $ ip a

For a more detailed guide on this, please refer to this answer

Hope it helped!

Note to comment of Silbee: Mind you, switching to the HWE stack kernel will severely limit LTE support, as they only come with 6 months worth of security updates.

Ubuntu 20.04 Server Not Recognising Ethernet Connection

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James H. Sterling

Ubuntu 20.04 Server Not Recognising Ethernet Connection

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James H. Sterling