Copyright law basically says that if there is any substantive creative input into a work's creation then the work is not only copyrightable, unless the author explicitly says different it's also copyrighted. Throw a paint filled balloon at a canvas and the resulting splatter is copyrighted. Consider: do more unforced choices, more optional choices, more creative choices go in to the production of a router configuration? Of course they do.
One can be snobbish about whether that qualifies as art, but it's certainly intellectual property (IP).
This assumes that Copyright is the only IP protection out there. There are actually two distinct realms of IP protection afforded in the US. Most other nations have a similar division. Copyright is for works of original creation, but cannot cover a process, practice, or device. Patents, on the other hand, cover processes, practices, and devices, etc. On a theoretical level, a network design and/or it’s documentation, configuration files, etc. could be and likely are copyright(-able,-ed). On a theoretical level, if you come up with some truly novel non-obvious reduction to practice of some particular process, you might well be able to patent it. While independent creation is a defense for copyright, it is irrelevant to a patent. Prior art can be a valid defense for a patent, but independently arriving at the same conclusion from independent development is not, in itself, a valid defense. (Showing that the patent is obvious, a minimal evolutionary step, or other such trivialization can be a valid defense.) However, all of the technicalities on this stuff vary from jurisdiction to jurisdiction. The broad strokes have been normalized through treaties for the most part, but details and technicalities still vary quite a bit. As such, if it really matters, get good local legal advice from all involved countries. Owen