I don't want to make this boring in troubleshooting length, so in short here is my current setup and latest glitch.
Mac Mini M4 on Sequoia 15.7.2 / Roon / Tambaqui
Let me work backwords. The problem is that roon finding my desired end point "Tambaqui on Ethernet". Roon finding Tambaqui on USB has never been a problem. Sequoia 15.7.2 is good now. 15.7.1 was working until 15.7.2 became available and thats when I was unable to make roon find my desired end point using ethernet. I did the software upgrade and all is fine now. For the longest time I had to run roon on USB and when I upgraded to 15.7.1 my ethernet end point started working again. The span of my troubleshooting pain stretches way back and I will not bore you with it.
I love how my Tambaqui sounds with roon using ethernet or usb. I have an itch to scratch now which is Pink Faun Scion sending to Playback MPD-8, but now I'm getting off track.