[wklie]

So it's Orbi router - Trendnet switch - dCS Upsampler. Correct?

I believe the Orbi router has 1000Mbps Ethernet ports.

What's your Trendnet switch model? Is it a 1000Mbps or 100Mbps switch?

What speed is your dCS Ethernet port running at? 1000Mbps or 100Mbps? If your Trendnet switch is a 1000Mbps Ethernet, it should show two different colors for the speed of a particular port so that you can find out it's running at 1000Mbps or 100Mbps.

If any of the above is running at 100Mbps, then one possible cause for the problem you were having might be related to how the 1000Mbps is made to run at 100Mbps, resulting in different network traffic patterns. The insertion of a switch to cure Roon playback is a common solution for another brand of network amplifier. Before that becomes common knowledge, Chris Connaker also found the same solution for an unspecified endpoint, described in a thread he created in his own forum.