Did you configure your Dlink router properly, its different than previous years since its useing a DHCP server instead of static ips.
If your router is configured properly then what OS and browser are you using, I know a few people that had a few problems with the mDns on Linux. Also if you go in command line and run the following command
Code:
ping roboRIO-4450.local
it will be able to tell you if its able to get a reply from your roborio.