Well, for one thing, you need to be more specific about what you need. I mean, if you have a passing knowledge of routers and drives, it's really little more than "plug and play" situation. Are you having a specific problem?
Aside from that, I too am looking for an answer somewhat related to this, tho not exactly. But that's why I clicked-in to see what the discussion what about. But you might be interested in this website that I ran across that deals with TM being used with external discs. Is yours connected via USB? If so, you might want to check this out:
...BTW, I just got a reply on my query of this subject from the folks I bought the external drive from (who shall go nameless) and this tech person said, in part: "Apple has gone back and forth on whether they support Time Machine via a network drive multiple times. The last I heard they do support Time Machine via a network drive."
So...beats me. I think it's time to ask the nephew who knows everything.