Roon Core Machine
Mac Mini 2011, Sierra. 2.3 Ghz, i5, 8Gb RAM, no screen attached.
In this case I use my iPhone as the remote device. iPhone is model XR, iOS 15.5. Roon App 1.8
build 988
Music is stored on a SSD (500Gb) at the Mac Mini, OS, Roon Core and Music are at the same disc.
Networking Gear & Setup Details
Router: Genexis Platinum 7840. I have no knowledge of YPN (never heard of it, can’t find details about it in the router).
WiFi network is AirTies, combined Air4920 and Air4930. AirTies base is connected through ethernet, while the wifi signal of the router itself is turned off. The speaker is connected to one of the 4930 devices.
Wifi if the Mac is turned of. It is connected by ethernet to the router.
Connected Audio Devices
There no need to add the complete HiFi set-up, because I did not use it: the music was played over Wifi using Airplay.
The Mac Mini is connected to the network using ethernet, Wifi settings of the Mac Mini are turned off, meaning the Mac used the wired connection to send the signal to the router, which uses a cable to send it to the AirTies base unit. Then it is transmitted by Wifi to the MusicCast 20 speaker. No MusicCast is used, it is simply Airplay.
The Yamaha MusicCast 20 has the latest firmware.
Number of Tracks in Library
9911 songs
Description of Issue
So what happened is that I replayed the first song if the playlist (which it did) while the screen showed the second song of the playlist was playing. When song no.1 was finished song no.3 started. Song no.2 never played.
So here is the more detailed version:
While playing Le Rempart by Vanessa Paradis I added the album Piano Piano by Jeremiah Fraites to the playlist. The album should start after finishing Le Rempart.
When Le Rempart was almost finished (within 2 seconds from the end) I touched [play back] to restart the song.
It did, but the screen said it started the first song of Piano Piano (Departure). Everything, the image and the progress bar seemed related to Departure (saying it would last 35 seconds). Vanessa went on…
I watched the progress bar to see what would happen. Le Rempart takes 3:11. Somehow I expected the playlist to jump to the second song of Piano Piano after 35 seconds, but it did not. The bar ended at 35 seconds and Le Rempart still played.
Oddly enough, at the left of the progress bar, the counter appeared to be the only item at the screen that had a sense of what was going on: it counted the seconds of Le Rempart.
When the song ended, he playlist jumped to song #2 of Piano Piano, thinking song #1 already had been played.
I did this again and the same thing happened. I found that doing this within the last 5 seconds of the song it would happen every time.
Roon does not have that much issues (or at least I can’t find them). If you are kind enough to add some more, I will get back soon! 
