I found that Ag plated copper wire ethernet cables make a nice improvement in the sound of streaming. Some can be had for just 5x the price of basic cheap ethernet cables. For short runs that isn't too bad. I run AQ Vodka to my streamer/player now from the audio grade network switch. The cables from the modem to router to network switch are AQ Cinnamon. The Vodka is a thick, stiff cable. The connectors are impressive looking and strong. Don't try using this cable in something with a plastic chassis.
Streaming 4K can for sure benefit from good ethernet cables. What a shame if some high end HT systems are not using better ethernet cables. I bought a long CAT 7 cable to run across the house from my listening room network switch to the HT system as an experiment. It made a significant upgrade to the streaming picture. It took me the better part of a day to run that cable through the walls, under the house and over to the HT system but well worth it. I have a Ag plated copper wire ethernet cable going from the wall to the Apple TV box. Would that I could buy a silver plated ethernet cable to run across the house. But I am very pleased with the picture.