eht0 = your 1st ethernet interface
http://www.voy.com/41165/ <-- the forum for Roaring Penguin
also, if u didn't already try to do a google for : "router name" "fedora core 3" and youll probably get some results, may want to try "router name" "fedora core 3" "dsl".
fedora core also has a forum / mailing list that may be of help.
from a fedora chat on a similar problem but with a different cause, "Have you checked system-config-network? " sounds like some type of graphical tool located in the menu perhaps.
here is the thread :
http://fcp.homelinux.org/modules/new...=10307&forum=6
its very long and boring but may help your brainstorming (but probably isnt ur issue meaning, your problem probably isn't an IRQ conflict like the guy in this thread)