The issue was ARP-related after all. Since all computers were cloned from the same image, the VMs ended up having the same MAC address, which caused collisions.

I think you need four distinct MAC addresses for this setup, are they all different?

We have a winner!

The classroom computers were mass-deployed using Clonezilla, from a disk image that already had the VM pre-configured. As a result, every VM had the same MAC address. Bridged networking put both hosts and both VMs in the same broadcast domain, which caused collisions in the ARP tables. I randomized the MAC address of one VM and everything suddenly started working.

It’s never been an issue since we’ve never needed to use anything other than the default NAT adapter, so I’ve never even questioned it. I found the solution after plugging the computers directly into an access switch without success, and cross-checking show mac address-table with the MAC reported by the VMs revealed that they were identical.

I checked ip neighbour (it also shows the ARP table, so I assume they’re identical), and it showed REACHABLE and STALE for addresses I could ping, but FAILED for the remote VM’s address. I will check arp -a when I get the chance, though.

I’ll give it a try tomorrow, thanks.

Although I’d still prefer to know why the VMs won’t talk over simple Ethernet.

Better not look at the microcode running on your CPU at a higher privilege level than the kernel, then.

Realistically, is that a factor for a Microsoft-sized company, though? I’d be shocked if they only had a single layer of redundancy. Whatever they store is probably replicated between high-availability hosts and datacenters several times, to the point where losing an entire RAID array (or whatever media redundancy scheme they use) is just a small inconvenience.

This is not meant for human beings. A creature that needs over 140 TB of storage in a single device can definitely afford to run them in some distributed redundancy scheme with hot swaps and just shred failed units. We know they’re not worried about being wasteful.

Something about child processes, maybe?

I’ve had good experiences with Rustdesk. The client is open-source and the no-cost server components (ID and Relay servers) are self-hostable. The remote server works on X11 and Windows. I use this script to run XFCE+Rustdesk in a headless session:

export SERVERNUM=69
export SCREEN_SIZE='-screen 0 2560x1440x24'
export DISPLAY=":${SERVERNUM}"
export XDG_SESSION_TYPE=x11

xvfb-run --server-num="${SERVERNUM}" --server-args "${SCREEN_SIZE}" startxfce4 & disown
sleep 1
flatpak run com.rustdesk.RustDesk & disown

Sunshine + Moonlight is also a good choice. I have Sunshine installed on a box at home and use Tailscale to connect to it from the Moonlight client. At 1440p 60 FPS it has no visible compression artifacts and responsive enough for gaming.

Even HDR is still “beta” on KDE iirc.

That’s a weird comparison because HDR is never going to happen on X.org (nor probably in the X11 protocol or clients). Wayland is being actively developed and the developers took it from something that can be made to work with some effort and some concessions to something that will reliably work in most cases. The year isn’t 1987 – software isn’t being written by nerds for nerds who can tinker and fix issues or add new features as a patchwork of unmaintainable code.

My home PC, about once a week, or whenever I have to install new software. My work PC, about once a month because the nvidia driver takes fucking ages to update because of DKMS.

As for the servers under my professional care… it depends. Most of the servers that I made run Debian that I update three times a year whenever the downtime is acceptable for the university (spring break, late summer, early december) or if a CVE needs fixing (e.g. xz-utils). One internet-facing server that I inherited still runs Ubuntu 16.04 because some teachers can’t possibly live without some legacy software and will throw a tantrum if upgrading is even mentioned – that one gets zero updates, and I got the dean’s promise in writing that I wouldn’t be held responsible for it.

The big virtualization server still runs ESXi 6 because the university didn’t want to pay for a lifetime license when it was available, doesn’t want to pay for a subscription now, and doesn’t want the downtime required to fully migrate to Proxmox VE. So it gets no updates. Plus it has a bad SSL cert and I need Chromium’s thisisunsafe to bypass the error.

It’s fucking rough out here.

Wayland has an actual future. It is being actively developed. Issues are being fixed and new features are added at least somewhat frequently. X11 might survive past the heat death of the universe, but it will be a stale, fossilized codebase maintained entirely by a small group of opinionated people.

My work PC has a 3080 and the latest nvidia-dkms in the Arch repo. I haven’t had a single display-related issue for probably a year.

c/linuxmemes

Look up where the word comes from if you want to be unreasonably angry.

That is the same kind of pedantry as claiming that ketchup is a smoothie because the tomato is a fruit.

Why do hikers travel to different mountains to conquer?

Neovim with Nvchad is what finally made me ditch pretty much all other IDEs. As much as I used to like Jetbrains, they’ve pivoted to vibe coding so hard that I can’t justify using their IDEs.