Update 2019-01-17
No Apple networking gear, only Mikrotik and Orbi. Roon doesn’t play to WiFi devices, though I can control Roon from those devices, and I can play the exact same files via any other media player that can read the network (Jriver, Plex, iTunes) on the same WiFi devices. So frustrating. Control Roon with my iPhone? Great. Playback to phone? NO. NO. NO. I even tried a freshly erased iPhone 6 with no other apps other than Roon. Again, it can control but not play. That suggests that something is awry with the app on the iPhone, doesn’t it?
I love Roon when I’m sitting there with my laptop reading interesting stuff and surfings my library, full-size stereo sounding sweet. I hate Roon when I’m working late at night and want to run it locally off my phone. I don’t understand why it can’t just play the damn music like literally every other music player I have. Infuriating.