Troubleshooting steps for why network suddenly stops working

[ProxyUser]

Hi

Can someone please help me troubleshoot why my network suddenly stops working. It has been working for months prior.

Note: proxmox has a single NIC that is eth0g10 (mapped to vmbr0) that is AQC107 Ethernet controller.

1. The lights stop blinking on the NIC and switch. Switching out cable or ports on the switch does nothing.

2. NIC shows up in the lspci -v:


3. System Logs: dmesg | grep atlantic




4. Showing all interaces available on the system: Output of ls /sys/class/net/

5. Proxmox's network configuration: Output of cat /etc/network/interfaces


6. NIC set to be called eth0g10 that will becomes vmbr0 in proxmox: Output of /cat/etc/systemd/network/10-eth0g10.link:



7. System network configuration: ip a


After reboot, system starts to work fine with eth0g10 showing up and dmesg | grep atltantic showing differently:

Thank you very much!

Best Regards

SMK

 

[shbaek]

Hi

Can someone please help me troubleshoot why my network suddenly stops working. It has been working for months prior.

Note: proxmox has a single NIC that is eth0g10 (mapped to vmbr0) that is AQC107 Ethernet controller.

1. The lights stop blinking on the NIC and switch. Switching out cable or ports on the switch does nothing.

2. NIC shows up in the lspci -v:
View attachment 83328

3. System Logs: dmesg | grep atlantic

View attachment 83329


4. Showing all interaces available on the system: Output of ls /sys/class/net/View attachment 83318

5. Proxmox's network configuration: Output of cat /etc/network/interfaces
View attachment 83319

6. NIC set to be called eth0g10 that will becomes vmbr0 in proxmox: Output of /cat/etc/systemd/network/10-eth0g10.link:

View attachment 83320

7. System network configuration: ip a
View attachment 83327

After reboot, system starts to work fine with eth0g10 showing up and dmesg | grep atltantic showing differently:
View attachment 83326
Thank you very much!

Best Regards

SMK

Things to Check​

• If the NIC and switch LEDs stop blinking, it could be due to power management settings (check BIOS/UEFI for "Wake on LAN" being disabled) or a driver issue.
• If lspci -v detects the NIC, but it's missing in ip a, the driver might not be loaded properly.

Solutions​

• Reload the driver:
  

  modprobe -r atlantic
  modprobe atlantic

  
  
• Restart network interfaces:
  

  systemctl restart networking

  
  
• Reset the PCI device:
  

  echo 1 > /sys/bus/pci/devices/0000:08:00.0/remove
  echo 1 > /sys/bus/pci/rescan

  
  
• Reinstall firmware/driver:
  

  apt update && apt install --reinstall firmware-realtek

  
  
• Check PCIe power settings in BIOS/UEFI (disable PCI ASPM).

Additional Checks​

• Run dmesg | grep atlantic to check for error messages.
• Use ethtool eth0g10 to verify link status.
• Recheck /etc/network/interfaces configuration.

If the issue persists, consider updating BIOS or testing a different kernel version.