Denon receiver airplay not detected by Roon App

[BlackJack]

From a something similar thread:

Scanning for Devices Misses Many (e.g. Marantz SR8802, Sony A80J, etc.)

Ok… Problem resolved. It was the QNAP firewall. I’ll have to figure out what needs to be added for passthrough… (e.g. the things mentioned by @CrystalGipsy, above) Anyone here running QNAP with Roon? And running the QNAP Firewall? Perhaps there’s a configuration file? Thanks, - s.west [edit] After having turned off the firewall, and subsequently discovering all the missing devices, I turned the firewall back on… and the devices remained… I suppose that this suggests the ‘multicast’ fail…

Maybe this helps you too.