Because mDNS usually doesn't work and just expecting it to work doesn't change that?
Router is all default except that I port-forwarded something. Funny enough, it sees the hostnames. I'm guessing it's some problem with both my computers, but no real need to fix this because I memorized the addrs already.
Maybe use an OS or DNS stack that isn't terrible?
Incredible asking for a not-broken DNS and IP stack is just too far out there when it seems most of the closed source OS platforms seem to manage just fine.
Or let me guess, you've specifically configured it to not "leak" such useful information?