I'm running ubuntu 11.10 (oneiric) on this machine, and suddenly, apt is unable to update properly.

If I ask it to update its package information, by running apt-get update (or alternatively telling the update manager to "check"), it succeeds for about 120 packages (more precisely, I get about 120 Ign/Hit notes) and then says it cannot find universe Sources and restricted amd64:

Hit http://de.archive.ubuntu.com oneiric-backports/multiverse Translation-en
Hit http://de.archive.ubuntu.com oneiric-backports/restricted Translation-en
Hit http://de.archive.ubuntu.com oneiric-backports/universe Translation-en
Err http://de.archive.ubuntu.com oneiric/universe Sources
  404  Not Found [IP: 141.30.13.20 80]
Err http://de.archive.ubuntu.com oneiric/restricted amd64 Packages
  404  Not Found [IP: 141.30.13.20 80]
W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric/universe/source/Sources  404  Not Found [IP: 141.30.13.20 80]

W: Failed to fetch http://de.archive.ubuntu.com/ubuntu/dists/oneiric/restricted/binary-amd64/Packages  404  Not Found [IP: 141.30.13.20 80]

E: Some index files failed to download. They have been ignored, or old ones used instead.

I manually checked the de server and cannot find anything wrong with the stuff it's complaining about. Also it looks pretty much like, say, the us mirror.
But oddly enough, the IP it lists, seems to point to a debian package server, which obviously does not contain ubuntu packages.

So, is this a local problem that I can fix somehow (and if so, how?) or is there actually some server down right now?