why does Omarchy hate my network?

[NixDarwin]

I like playing with different Linux distros, but don't have enough machines to dedicate one to each distro. So I run Proxmox and pass my Intel IGPU and XHCI controller through to one VM at a time. This allows me to easily switch between different versions of Linux, but since each one gets full control of the USB and display, they feel "native." It works great for switching between Debian, PopOS, NixOS, and even works fine for installing Omarchy. But once the installation is finished, Omarchy becomes effectively unusable, because networking frequently "freezes up."

For several seconds at a time, only while running Omarchy, the network is totally unresponsive. Ping, for example, will run fine for a bit, then drop all packets for a while, and then start working again. If I leave ping running for long periods of time, it reports around a 75% packet drop rate.

• The problem does not happen with other Linux VMs running on the same Proxmox instance. Multiple different Linux distros all work just fine using exactly the same settings as my Omarchy VM.
• The problem is not with the hardware. I tested running a large download on the Proxmox host while Omarchy was running. Omarchy did the "freeze up" thing, but the download running on the Proxmox host was not affected.
• I've tried different versions of the Linux kernel, in Omarchy, but that had no impact.
• I've tried using different types of network interfaces in Proxmox, but that had no impact (and all the other VMs work just fine with the standard virtio network interface).
• To rule out it being an Arch thing, I installed Manjaro in another VM. That VM works just fine, and I'm using it to post this, now.

Can anyone offer any suggestions on where I should look to find out what is causing these network "freezes?"

[NixDarwin]

BTW, I have tried reinstalling a few times. I'm installing from ISO and tried the latest (3.1.1), today.

[NixDarwin]

Oh, and of course there are many other devices on the same network that are all working, fine.