How to fix: Receiving "404 Not Found" HTML when building basic prereq derivations?

This has happened with more than one derivation now: The first time it was with something to do with bash (was written <hash>-bash44-010.drv or similarly I believe), now it’s something to do with binutils (<hash>-binutils-2.34.tar.bz2.drv).

I am trying to build a flake via nix build '.#<name>' when I get this error, the message in particular looks like:

error: --- Error --- nix-daemon
builder for '/nix/store/ksw35rg7jzxfhrrw2rvvrx71lzfjv1q7-binutils-2.34.tar.bz2.drv' failed with exit code 1; last 10 log lines:
  response body:

  <head><title>404 Not Found</title></head>
  <center><h1>404 Not Found</h1></center>

Attempts to build build derivations which require this one then of course fail, causing the build to fail.

There’s no voodoo going on with my network afaict, connections are fine and web-browsing is fine. And I don’t think I’m really trying to really build anything exotic, pretty much a pared down version of mjlbachs nixpkgs in his dotfiles.

Has anyone else run into this and/or figured out a cause/fix?

Hm, so after attempting to build this several times over a couple days, this error has been very inconsistent.