First thing to try would be power down all the devices, then bring them up one at a time, starting with the router.
1. Shut down unraid, all pc's in the house, then unplug the router.
2. Bring up the router, wait for it to completely connect, then power on unraid, let it boot, power on computers one at a time, check to see if they can resolve the name.
Be sure to give things time to settle, sometimes windows can take a while to figure things out.