I've certainly had this sort of error when there was a proxy set up  (e.g. in /etc/apt/apt.conf.d/... or similar). Or NOT set up, and you're using one for wget.

FYI, apt proxy config looks something like:

Acquire::http { Proxy "http://127.0.0.1:3142"; };

Other nastier options:
a) they're behind some kind of firewall proxy that drops/rejects connections without a password.
b) Someone got creative with IPtables and they've got per-user firewalling rules... (I can't remember... doesn't apt(-get) drop privs for fetches?)

David