“When the network dies at 2am, you learn to love ethtool. And kernel pinning. And backups.” - Homelab incident retrospective

“Game over, man! Game over!” - Aliens. When the NIC goes dark mid-backup, it feels that way. But there’s a fix. Proxmox hosts with Intel I217/I219 NICs (e1000e driver) can lose network connectivity under load. Backups freeze. VMs go dark. Unplugging and replugging the cable sometimes brings it back. This is a kernel regression - not your hardware.

“The network just… stopped. Ping works from the switch but not from my laptop.” - Every homelab operator at 2am

Symptoms

What you see When it happens
Network interface shows UP but no traffic During or after backups
SSH hangs, web UI unreachable Under sustained load (sync jobs, VM migrations)
dmesg shows e1000e: Detected Hardware Unit Hang Sporadically
Unplug/replug cable restores connectivity Until next heavy traffic

Affected NICs: Intel I217-LM, I219-V, I219-LM, and similar onboard gigabit controllers. The e1000e kernel driver has regressions in Proxmox kernels 6.8.12-9-pve and newer (including 6.17.x). Your PCI I350 or other Intel NICs using the igb driver are fine.

Root Cause

A regression in the e1000e driver’s hardware offload path. Under load, the TSO/GSO/GRO path can hang the NIC. The driver thinks the interface is up; the hardware has effectively frozen.

ℹ️ Info

This has been reported across Proxmox 6.8.x, 8.x, and kernel 6.17.x. The Proxmox forum thread has dozens of confirmations. Intel I210 (igb driver) does not have this issue.

Two Fix Options

Option Approach Pros Cons
A. ethtool workaround Disable offload features on the affected interface Stays on latest kernel; widely confirmed Slight CPU overhead
B. Kernel pinning Boot from an older kernel (e.g. 6.8.12-8-pve) No config change to NIC Stuck on old kernel until upstream fix

Recommendation: Try Option A first. It works for most people and lets you keep current security patches.

Step 1: Identify the interface

SSH to your Proxmox host:

# Find the I217/I219 (e1000e) interface
lspci -k | grep -A3 -i "e1000e\|219\|217"

# Interface name (often eno1 or enp0s31f6)
ip link show

The interface in use will typically be eno1 or enp0s31f6. In my case it was eno1 on a Dell OptiPlex 7080 with I219-LM.

Step 2: Apply immediately (no reboot)

sudo ethtool -K eno1 gso off gro off tso off tx off rx off rxvlan off txvlan off sg off

Replace eno1 with your interface name. Connectivity stays up; the fix takes effect instantly.

Step 3: Make it persistent

Edit /etc/network/interfaces and add a post-up hook under the interface block:

# /etc/network/interfaces
iface eno1 inet manual
    post-up ethtool -K eno1 gso off gro off tso off tx off rx off rxvlan off txvlan off sg off

auto vmbr0
iface vmbr0 inet static
    address 192.168.1.131/24
    gateway 192.168.1.1
    bridge-ports eno1
    bridge-stp off
    bridge-fd 0

If eno1 is already a bridge port (as above), the post-up runs when the interface is brought up. Reboot to verify it survives a restart.

💡 Tip

On Proxmox, eno1 is often the bridge slave for vmbr0. The post-up runs during ifup vmbr0 before the bridge attaches. No need to modify the bridge block - just add the post-up to the physical interface.

Step 4: Verify

sudo ethtool -k eno1 | grep -E 'generic-segmentation-offload|generic-receive-offload|tcp-segmentation-offload'

Expected output:

tcp-segmentation-offload: off
generic-segmentation-offload: off
generic-receive-offload: off

Option B: Kernel Pinning

If the ethtool workaround doesn’t help (or you prefer not to change NIC settings):

# List available kernels
proxmox-boot-tool kernel list

# Pin to previous working kernel (e.g. 6.8.12-8-pve)
proxmox-boot-tool kernel pin 6.8.12-8-pve

# One-time test (next boot only)
proxmox-boot-tool kernel pin 6.8.12-8-pve --next-boot

# Unpin when fixed upstream
proxmox-boot-tool kernel unpin

Reboot after pinning. You’ll stay on that kernel until you unpin.

⚠️ Warning

--next-boot is temporary. Use proxmox-boot-tool kernel pin <name> without flags to make it permanent. Otherwise you’ll boot back into the broken kernel after the next reboot.

Why This Works

“Sometimes the fix is ‘turn off the optimization.’ The kernel has bugs. Workarounds are valid engineering.” - Kernel regression survivor

The ethtool fix: Hardware offloads (TSO, GSO, GRO) move packet segmentation and reassembly into the NIC. The e1000e driver’s offload path has a bug - under load it can hang the hardware. Disabling those offloads forces the kernel to do the work in software. Slightly more CPU, but the NIC stays stable.

Kernel pinning: The regression was introduced in a specific kernel release. Older kernels don’t have the bad code path. Pinning avoids the problem entirely at the cost of not getting newer kernel fixes.

Real-World Result

On a Dell OptiPlex 7080 (I219-LM) running Proxmox 8.x with kernel 6.17.9-1-pve:

  • Before: Network died during backups; required cable unplug/replug.
  • After: ethtool workaround applied + persistent config. Backups run without interruption.

No kernel downgrade. No hardware replacement. One post-up line.

References