ASUS NUC 14 Essential with Core 3 N355 CPU -- Ethernet found by Ubuntu 24.04.2 but inop

[jimbobstpaul]

Hi.

I am by no means good at troubleshooting Linux, but I have built dozens of computers (many of them various distros of Debian-based Linux) over the years, and helped many people with their computer stuff, and I have never had even one problem with Ethernet connections to the Internet.

Here is my current problem, no Ethernet connection to my LAN:

Ubuntu Version: Ubuntu 24.04.2 LTS

Desktop Environment: ubuntu:GNOME

Problem Description:

No Ethernet Connection shown in NetworkManager, and of course therefore no Internet access via Ethernet.

I am doing all this work on the target system, using its WiFi connection, which always works.

I tried following the instructions at the recommended “Start here” page

Network Connection Troubleshooting at discourse.ubuntu.com:
Network Connection Troubleshooting

and nothing seems to help, but I am now convinced I posted my stuff in the wrong location, or with an unhelpful Title/Topic Name, so I’m trying again, now in this location with a new topic name.

Relevant System Information:
A new (1-week old) ASUS NUC 14 Essential Barebones with the “top-of-the-line” Intel Core 3 N355 CPU option (Model # NUC14MNK35*), and these two items added:

Kingston RAM: Fury Impact 16GB 4800MT/s DDR5 CL38 SODIMM XMP Ready Laptop Memory Single Module KF548S38IB-16
https://shop.kingston.com/products/impact-ddr5-laptop-memory?variant=41738521968832

Crucial P3 1TB PCIe Gen3 3D NAND NVMe M.2 SSD, up to 3500MB/s - CT1000P3SSD8

Screenshots or Error Messages:

lspci output includes this one item relevant to Ethernet:
01:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller [10ec:8125] (rev 0c)
Subsystem: ASUSTeK Computer Inc. RTL8125 2.5GbE Controller [1043:88e8]
Kernel modules: r8169

The computer’s “BIOS” / UEFI setup screen shows the LAN controller Enabled.

What I’ve Tried:

I have tried both the CLI and GUI versions of NetworkManager and similar tools, and I messed around (Newbie) in them and somehow succeeded in adding an entry called “Ethernet connection 1” (it wasn’t there before I did that) and I entered the correct Ethernet MAC address from the computer’s Setup screen, then I did

james@NUC14Ess:~$ sudo systemctl restart NetworkManager
and that ran with no complaining, and the network indicator at top right of my screen apparently really does restart (it “winks out” for about two seconds then reappears as before), but still no joy, and it doesn’t show up as the “Device” in this report:

james@NUC14Ess:~$ nmcli connection show
NAME                   UUID                                  TYPE      DEVICE 
Home-N                 c3289016-c905-488a-990f-b2ccacdb40be  wifi      wlo1   
lo                     198d2940-7150-4a14-9908-935c4fffa7bd  loopback  lo     
Ethernet connection 1  14dfe36f-93f6-4854-a1f5-fdf685c395af  ethernet  --     
james@NUC14Ess:~$ 

I disconnected the cable from the Gigabit Ethernet hub in the Study to a working_device (the VoIP adapter, which has been working for about 15 years) and plugged it in instead to the Ethernet jack on the NUC, where it has been through all this testing, and yes, I did re-seat it and I did hear it “click”.

In case it matters: There are lots of complaints on various forums of baffling Ethernet problems in Ubuntu 24.04.x. There are even some on this forum that appeared in the last few days.

I will greatly appreciate any ideas for further troubleshooting, driver installations, etc…

Sincerely,

Jim Harris

[jimbobstpaul]

NOTICE – URGENT – Here is the fix!

@Jeremy31 sent me a fix and I installed it and it works!

See my Topic/Thread

[I'm trying to use the wireless-info script, but Pastebin isn't offered]

I strongly recommend you pass this on to:

• Ubuntu Release staff (at Canonical?) to let them know they need to include that r8125 thingie or whatever it is that @Jeremy31 and I did to fix the problem (I don’t understand it fully; I just followed his step-by-step instructions and rebooted and it worked), and they need to hurry, because there are a lot of people who will have the same mysterious failure of their Ethernet until it is fixed.
• ASUS to let them know that they need to have their sellers add a slip of paper to every package shipping one of the whole family of NUCs that this missing feature affects (you have the details in my Original Post), and add it to their WWW site about them, and include it in their invoices/order info, etc… This is a HUGE problem that ASUS must not be aware of, because I called them a couple days ago and I got a Return Material Authorization, because they promise to support their product when it is running Ubuntu 24.04.x LTS, and they think they need to repair the NUC and ship it back to me, and there is nothing wrong with it!

Thanks to everyone on this forum that makes this kind of problem-solving available!

Best regards,

Jim Harris