Fixing degraded Promox VE + Intel I350/X552/X557-AT NIC performance after v8 update

I use Proxmox VE on my custom home microserver, Vakt. Upon updating from version 7 to versions 8.1-8.2 a few months ago, I’d noticed degraded performance from the four Ethernet ports on the system, causing additional latency and some packet loss.

Vakt is based on a SuperMicro X10SDV system-on-board. Two 10GBASE-T ports are provided by a “X552/X557-AT” controller built in to the Xeon SoC, and two additional 1000BASE-T ports are provided via an Intel I350-T2 controller.

All four ports were affected, so I suspected a driver regression. And indeed, reverting to kernel version 6.1.10-1 has solved those performance issues until upstream fixes the bug.

Here’s how to do it:

# find available kernels for your system with `apt search pve-kernel`
# I selected pve-kernel-6.1 in this case, which installs 6.1.10-1
apt install pve-kernel-6.1

# 'pin' the kernel
# normally the system automatically maintains the boot config to use the most suitable kernel
# this is telling it to use the old kernel we just installed instead
proxmox-boot-tool kernel pin 6.1.10-1-pve


# revert the changes with `proxmox-boot-tool kernel unpin && apt autoremove`
# you can see which kernels are installed and whether any are pinned with `proxmox-boot-tool kernel list`