Firefly has an mDNS responder built-in. You shouldn’t need Bonjour running on the PC. NSLU2’s & ReadyNAS’ certainly don’t. I have both & I don’t have Bonjour running on my PC.
Chances are your router, being a D-Link, is not handling multicast properly and your PC is somehow fixing the problem.
Other D-Link routers don’t work properly with Firefly & I wouldn’t be surprised if all of them had problems.
Check your router for settings labelled UPnP, IGMP or WMM.