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RTL8125 Ethernet controller disappeared from PCI bus after system update #353

@Molotovsk

Description

@Molotovsk

After updating my CachyOS system today, my Realtek RTL8125 2.5GbE Ethernet controller completely disappeared from the PCI bus. The device was not visible in lspci in either Linux or Windows.
I have been running CachyOS for a while and have done many system updates without any issues. This is the first time this has happened.

Hardware:
Motherboard: ASUS TUF GAMING B650-PLUS
Network chip: Realtek RTL8125 2.5GbE (onboard)

What happened:
System was working normally with r8125 driver loaded, ran Cachy-update at 08:06 on 2026-02-17
After reboot, ethernet was completely gone
lspci showed no Realtek device at all
ip link only showed loopback
Booting into Windows also showed no network adapter.

Tried booting with linux-cachyos-lts kernel — same issue
Checked BIOS: Realtek LAN Controller was set to Enabled
Tried restoring from btrfs snapshot — no change.

Solution:
Full BIOS update (unsure if this helped at all), and also a full power cycle. Shut down completely, unplugged power cable from PSU, held power button for 30 seconds, waited approximately 3 hours, then powered on. The network card reappeared and now works normally.

Packages updated in the problematic session:
linux-cachyos 6.19.0-2 -> 6.19.2-2
linux-cachyos-lts 6.18.10-2 -> 6.18.12-2
linux-cachyos-headers 6.19.0-2 -> 6.19.2-2
linux-cachyos-lts-headers 6.18.10-2 -> 6.18.12-2
linux-cachyos-nvidia-open 6.19.0-2 -> 6.19.2-2
linux-cachyos-lts-nvidia-open 6.18.10-2 -> 6.18.12-2
networkmanager-qt 6.22.0-1.1 -> 6.23.0-1.1
gstreamer 1.26.10-5 -> 1.28.0-2
btrfs-progs 6.17.1-2 -> 6.19-1

Bug report log file
https://paste.cachyos.org/p/5007ce7.log

Logs:
Last working boot before I updated — r8125 loaded successfully:
feb 17 09:05:24 kernel: r8125 Ethernet controller driver 9.016.01 loaded
feb 17 09:05:24 kernel: r8125 0000:08:00.0 eno1: renamed from eth0
feb 17 09:05:30 kernel: r8125: eno1: link up
https://paste.cachyos.org/p/5b20491.log

First boot after update — no network hardware detected:
No r8125, realtek, or ethernet entries in logs at all — device not on PCI bus
https://paste.cachyos.org/p/befcf4d.log
Full pacman log from update:
https://paste.cachyos.org/p/e49f734.log
System info:
https://paste.cachyos.org/p/9c0a1cd.log
lspci -nnk (after fix):
https://paste.cachyos.org/p/007ea2e.log

I don't know if this is related to the kernel update, a firmware interaction, or something else but it happened immediately after this specific update. I'm reporting this in case others experience the same issue or if it helps identify a potential problem.

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