Damn. So, that was a week. It all started on a high note, you know? I’d just finished a marathon session getting BookStack and a new GitHub runner purring away on the cluster. I went to bed actually happy, dreaming of the glorious documentation I was about to write, finally getting my homelab in order. The next day at work was fine, just buzzing with plans for the evening. I was on a call with some friends, showing off the latest addition to my digital empire: a Pterodactyl server for hosting games. I proudly pulled out my phone, and opened the browser to the server’s local IP. A feat possible due to my Tailscale VPN system; I’m part of my home network no matter where I am.
“Check this out,” I said, turning the screen to the camera. And then… a little spinning icon that eventually gave up. “Huh, weird,” I mumbled, trying another one of my internal sites. Nothing. All of them. My entire private stack was a digital ghost town. The freak-out began. I frantically pulled up my Tailscale admin panel. There, blinking like a lone survivor in a zombie apocalypse, was my Synology NAS. Every other client — all my Proxmox hosts, my VMs — offline.
The second, more intense, freak-out began. I tried to remote into my home PC with Parsec to get a look at the console, but it wouldn’t connect. Of course it wouldn’t! The whole DNS chain was broken, even though I did not know the extend. My phone’s DNS queries are supposed to be intercepted by Tailscale, which would normally resolve the internal hostnames. But since the hosts were down, Tailscale wasn’t running! Even if it was, the request would then fall back to my AdGuard Home instance… which, of course, was also down because it runs on the cluster! I had to call my wife — who, being cool like that, knew exactly what I meant — and asked her to toggle Tailscale on my PC so I could get in. And after she toggled it off, I could connect! But then I could reach NONE of my homelab IPs. That is when I realized that it was ALL down! Not just Tailscale or AGH. Everything.
After what felt like the longest workday ever, I got home. And there it was. On every single monitor connected to every single Proxmox host, the same cryptic, angry text was scrolling: “enp2s0: NETDEV WATCHDOG: CPU: 3: transmit queue 0 timed out”. My heart sank. It wasn’t one host. It was all of them. My mind immediately jumped to the worst-case scenario: a full rebuild. Days of work, reinstalling Proxmox on every host, painstakingly restoring every VM and container from backups. It was a nightmare vision. But before resigning myself to that fate, I hit the internet. Hard.
I dove headfirst into a rabbit hole of Proxmox forums and r/homelab posts. A pattern emerged around kernel updates and the finicky in-kernel r8169 driver for Realtek NICs. The fix, people said, was the vendor-specific r8168-dkms driver. But as I read on, I saw posts from people where even that failed. The key difference for the successful ones? A package I’d never thought about: pve-headers. I read on: the driver is a kernel module, and to build that module, the system needs the kernel’s blueprints — the headers! DKMS is like a tailor trying to make a suit for a new kernel. Without the kernel’s measurements — the headers — it can’t do anything! The kernel upgrade process itself was invalid because this crucial package, which isn’t installed by default, was missing. That explained the Realtek hosts, but what about the Intel ones?
More searching. And then I found it: Quorum. I learned that a Proxmox cluster is a direct democracy; to function, it needs a majority vote. In my 4-node cluster, that meant at least 3 nodes had to be online. When my two Realtek hosts dropped off the network, the cluster lost its majority. As a safety protocol, the two remaining Intel hosts automatically fenced themselves off. It wasn’t four separate failures; it was one root cause that created a catastrophic cascade.
Now I had a plan, but I needed to get one host online. With no monitor output until the kernel loaded, I was flying blind. I hit the power button and just started rhythmically tapping the down arrow key, praying I’d catch the GRUB menu at the exact right second. Many tries failed and it loaded in with the bad kernel and the same error messages. But one time the screen stayed black. I figured “maybe???” and on a whim, I hit Enter, guessing I’d landed on ‘Advanced options’. I tapped the down arrow twice more, a blind guess to skip the ‘recovery’ entry and select the previous, working kernel. I hit Enter again, sighed, and walked away, convinced it had failed. But a few minutes later, checking my laptop out of sheer habit, a ping came back. It was online! That desperate, blind sequence of keystrokes had actually worked! The host was alive. From there, the great un-bricking could begin. On each host: add the non-free repo, install the now-obviously-critical pve-headers, install r8168-dkms for the Realtek machines, and run a full system upgrade. One by one, I brought them back from the brink. And now? Everything is back. Not just back, but better. The kernels are all aligned, the right drivers are in place, and the headers are there to make sure this never, ever happens again. The relief is immense. No rebuild, no restoring from backups. Just a whole lot of frantic learning and a newfound respect for the awesome, terrifying power of cluster quorum. And a puzzle; why oh WHY do they allow the pve-headers not to be installed by default?