Ethernet vs 5G Streamer Tech Considerations for Sound Quality

Experiment #1: plug Ethernet cable. Listen

Experiment #2: unplug Ethernet cable, connect via WiFi. Listen

Then use whichever method of connection you like more going forward. 
If you hear no difference, use whichever is most convenient for you.

That is all you need. All that you can do yourself. Why search for technically documented justification in the Internets?

I have two situations.
Main System - From my modem-router location to my main system requires about 40+ feet of hard cabling allowing for how the cable must be run. Initially, I ran 50 feet of hardwired Ethernet cable and recently replaced that with 15M of fiber using two converters, one at the modem-router location and one at my main system that I use with a LPS. 
I have a second system located in my garage that provides music to our outdoor area.  That system is much further from my modem-router location.  A year or so ago, I switched my router to an Orbi mesh system.  The mesh system provides full internet bandwidth from multiple satellites that can be positioned wherever you choose.  By positioning one of the satellites in the garage, I was able to hardwire a very short Ethernet cable from that Orbi satellite to a second Roon endpoint that feeds the garage system from my hardwired server.  

Mitch2 sounds like you had a fair amount work and expense getting main system set. I do have an orbi system as well but my main router signal is solid so I use that, less “devices” touching path I guess.
thyname, of course I can do A/B/A and have, didn’t need that wisdom smh....was just seeing if anyone had any hard data or justification for all the optical rendu and $1000 ethernet cable proponents vs 5G which is indeed a zero additional cost.