[TUTORIAL] Realtek 8125 NIC not working on Proxmox with X870E motherboard (no network)

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YLsutudio

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Apr 9, 2025
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Hello,

I'm having a serious issue getting the network interface to work on my new system using the **X870E motherboard** (which includes the **Realtek RTL8125 2.5GbE NIC**).

After installing Proxmox VE (both 8.1 and 8.2 tested), no network interface is detected at all. Running `ip a` only shows the `lo` interface (loopback), and `lspci` confirms the NIC is present:


I also tried loading `r8169` and building the latest **Realtek r8125 driver** from source (v9.015.00), but the NIC is still not recognized or usable. I’ve verified that the firmware files (e.g., `rtl8125b-2.fw`) exist in `/lib/firmware/rtl_nic/`, but it doesn’t help.

This system currently has **no internet access**, which makes it very hard to fetch packages or build modules inside Proxmox.

### What I've tried:
- Modprobe `r8169` (results in "unknown chip XID 688")
- Compiling r8125 from official Realtek source
- Copying required firmware manually
- Using Debian 12.5 base image to test (same result)
- USB Ethernet dongle (works)

I believe the RTL8125 chip on this board is not supported out-of-the-box in the current kernel (Proxmox 6.2/6.5/6.6) or is missing required firmware/module support.

Any suggestions or official workaround for Proxmox to properly support RTL8125 (especially on X870E chipset boards)?
Would really appreciate your help.

Thank you!
 
I asked AI for a solution to this same problem.
Grok wasted my life
Perplexity almost got it figured out ....but then bricked my system.
ChatGPT got the NIC running. But then couldn't get the DKMS configured - so I fear an upgrade will return me to bad/no NIC driver.

If you, are anyone else, has a complete answer please post here.

Thanks!

I really don't know how I got here....I just followed Google maps. :)
 
hi,

As you have already guessed, the RTL8125 chip is not yet supported in Proxmox VE Kernel 6.8.*.
You now have two options:
1. you stay with the 6.8.* kernel and get our r8125-dkms package (This also requires the correct headers proxmox-headers-6.8 and dkms)
2. you get our new kernel package proxmox-kernel-6.14 which supports the driver

Both options require you to download a package from our repositories.
The easiest way would be to download them from our repositories with some other debian system which has internet.
1. You have to add our repositories to you apt sources /etc/apt/sources.list [0]

2. Then as precaution clean your cache: apt clean

3. Download the debian package apt install --download-only <package_name>

4. Load it on the server with an USB drive or something comparable

[0] https://pve.proxmox.com/wiki/Package_Repositories#sysadmin_no_subscription_repo
 
hd-- said:
hi,

As you have already guessed, the RTL8125 chip is not yet supported in Proxmox VE Kernel 6.8.*.
You now have two options:
1. you stay with the 6.8.* kernel and get our r8125-dkms package (This also requires the correct headers proxmox-headers-6.8 and dkms)
2. you get our new kernel package proxmox-kernel-6.14 which supports the driver

Both options require you to download a package from our repositories.
The easiest way would be to download them from our repositories with some other debian system which has internet.
1. You have to add our repositories to you apt sources /etc/apt/sources.list [0]

2. Then as precaution clean your cache: apt clean

3. Download the debian package apt install --download-only <package_name>

4. Load it on the server with an USB drive or something comparable

[0] https://pve.proxmox.com/wiki/Package_Repositories#sysadmin_no_subscription_repo
Click to expand...

So just to confirm, if I update to the 6.14 kernel, I won't have to do the headers or the dkms package like I did on Proxmox 8.3 any more?

Edit: On 8.3 I manually had to do the r8125-dkms process and it did work.
 
Last edited:
Trying to piggyback off this thread and get my Realtel 8126 chipset NIC working on a X870E board too :)

Forgive my ignorance, but now that I have completed the above 4 steps in your tutorial above, and have the packages loaded on the non-functional VE machine...is there a tutorial on how where to place the packages (/how to enable them) after that point?
 
@hd--

Even with the 6.14 kernel, I had to install the pve-headers for this kernel version and the r8125 dkms package to restore connectivity.
 
Hmmm - This is quite strange

I have two r8126 cards - One seems to work on 614....One does not. I have them both bridged and I can connect through the one that goes via access point, but not the one direct to my desktop

I can see the r8126 driver is loaded for both. I can see interfaces for both
 
OK - Ignore

r8126 seems to work on pve-6.14.0.2 kernel.....Problem was with a recent arch update on the other side...

Honestly - The driver comes and goes working with updates - even on lts - What a nightmare
 
Giggling3999 said:
Hmmm - This is quite strange

I have two r8126 cards - One seems to work on 614....One does not. I have them both bridged and I can connect through the one that goes via access point, but not the one direct to my desktop

I can see the r8126 driver is loaded for both. I can see interfaces for both
Click to expand...
Is r8126 different from r8125?

My motherboard supports 2.5G, are you 2.5G or 10 or 1?
 
Giggling3999 said:
r8126 is the 5G model
r8125 is the 2.5G model
Click to expand...
Alright, I have the 2.5G model which is what I want to work consistently between updates like @hd-- posted.

hd-- said:
hi,

As you have already guessed, the RTL8125 chip is not yet supported in Proxmox VE Kernel 6.8.*.
You now have two options:
1. you stay with the 6.8.* kernel and get our r8125-dkms package (This also requires the correct headers proxmox-headers-6.8 and dkms)
2. you get our new kernel package proxmox-kernel-6.14 which supports the driver

Both options require you to download a package from our repositories.
The easiest way would be to download them from our repositories with some other debian system which has internet.
1. You have to add our repositories to you apt sources /etc/apt/sources.list [0]

2. Then as precaution clean your cache: apt clean

3. Download the debian package apt install --download-only <package_name>

4. Load it on the server with an USB drive or something comparable

[0] https://pve.proxmox.com/wiki/Package_Repositories#sysadmin_no_subscription_repo
Click to expand...
 
Even with the 6.14 kernel, I had to install the pve-headers for this kernel version and the r8125 dkms package to restore connectivity.
Click to expand...
did you check if the r8169 driver was mapped to the NIC?
if you issue lspci -v, you should see something comparable to the following lines for the Ethernet controller
Code: 
Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8125 2.5GbE Controller (rev 0c)
[...]
Kernel driver in use: r8169
Kernel modules: r8169
 
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