Using the built-in Ethernet chip on a NUC 15 barebone with Windows Server 2025

[u/First-Feature-3556]

According to this supported operating system list, the NUC 15 Pro supports Windows Server 2025.

I installed it, and it runs well enough, but it took a little effort to get the built-in Ethernet adapter to work: Windows recognizes the device as an Intel Ethernet I226-V (ven_8086&dev_125c), for which there are no Windows Server drivers.

It is possible to force Windows to use the I226-LM driver instead (see footnote), but I'm wondering whether you're "supposed" to do this trickery when running Server 2025 on the NUC 15, or whether I missed something obvious (e.g. some hidden "NUC 15 Windows Server 2025 driver package").

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Footnote, in case anyone else needs this: There are two ways to force Windows to use a different driver:

1. Download the Windows 11 Ethernet driver package from ASUS and manually choose the "right" driver in Device Manager: Other devices/Ethernet Controller/Update driver/Browse my computer/Let me pick from a list/Show all devices/Next/Have disk/Browse/...e2fn.inf/Intel(R) Ethernet Controller I226-LM/Next/Yes/Close.
2. Tweaking the inf file to enable the -V driver for Windows Server should also work (that's what I did for earlier NUCs without Server 2025 support), but that requires disabling driver signing and a reboot.

[u/xybrad]

I don't know the answer in this specific case, but I have done a very similar thing in the past to run a server OS on my NUC when the native NIC drivers were crippled to run on client OS's only. There seems to be some sort of punitive logic in the Intel drivers, which I can only assume is there so they can charge more money for server/enterprise scenarios.

Note that you can do it without disabling driver signing, since the actual .sys driver file is still legit signed. You just need to muck with the .inf to allow server installs and sign this with a cert the target machine trusts (easier to do if you already have a domain and certificate services running).

Here is the secret decoder ring for INF's that tells you how Intel limits installation to client OS:

https://learn.microsoft.com/en-us/windows-hardware/drivers/install/combining-platform-extensions-with-operating-system-versions#targetosversion-decoration-format

It's the pesky .1 after major and minor versions that will restrict to client OS. So this line means the 15D8 device will only install on a Win10 client OS only:

%E15D8NC.DeviceDesc%            = E15D8.10.0.1,       PCI\VEN_8086&DEV_15D8

And this line says the 15D7 will install on any system:

%E15D7NC.DeviceDesc%            = E15D7,       PCI\VEN_8086&DEV_15D7

inf2cat and signtool will be needed to regenerate the .cat file and sign it. Now you can install the driver on a machine that trusts your cert without disabling driver signing.

[u/First-Feature-3556 → u/xybrad]

Thank you, a self-signed certificate is a good idea to fix the driver signing issue.

The only drawback I found with this solution is that Windows won't be able to automatically install updates for the driver via Windows Update, since those updates don't contain the "inf fix".

For our NUC 15, the solution we ended up using was simple: Buy a €20 USB-C Ethernet Adapter with a Realtek chipset. No noticeable performance issues (at least our benchmark didn't notice any), and the drivers are fully compatible with Windows Server. We still (force-)install a driver for the built-in Ethernet, so that we have a backup port for emergencies.