mDNS
In the past few weeks I have been exploring mDNS and IPv6. Your router doesn't provide local DNS? Not an issue, add .local to the hostnames and boom, everything works.
For example, run `python3 -m http.server` on your laptop, then open the browser on your phone and browse yourlaptopname.local:8000 ! There's more, services are advertised on mDNS, that's how your printer magically appears on your computers and phones.