I was unable to use AirPlay and MusciCast and after a Yamaha customer service call have now found a solution.
My network has three separated SSIDs - one main LAN and two virtual LANs (VLANs). My household uses the main LAN and keeps one separate VLAN for guests, and another VLAN for Internet of Things (IoT) to keep these poorly-secured devices separate from family and guests. AirPlay and MusicCast just would not function on either of my two VLANs; they require the main LAN. I don't know how general this restriction is, though I cannot determine any real differences between LAN and VLAN setup on my router.
Here's the setup procedure that worked:
1. DHCP On - don’t need a static IP address.
2. On iPhone “Forget” all SSID networks but the main one - if there are VLANs, definitely forget them. When Yamaha says “Use the SSID at the top of the list,” believe them. This was key on my setup.
3. Join the Yamaha receiver to the main WiFi network in #2
, above. There are several ways to do this.
4. Receiver and playback device (my iPhone) must be on the same WiFi network and must remain on it during playback.
5. Use MusicCast Controller app to log in. App needs initial permission for Library and probably location (I turned that off later). It doesn’t need permission later for volume (handy, though) or analytics, so I turned the latter off. I did name the receiver location “Living Room” and this name shows up on the iPhone when initiating AirPlay as the speakers I want to play. If MusciCast Controller works, AirPlay will probably work - mine did.
Most people have and use only one WiFi network. With that, AirPlay and MusicCast should set up well, though I prefer to maintain my separate SSIDs for security. If you're having trouble setting them up, give these steps a try.