Like several others here, I have a technical background - ECE degree, been involved professionally with computer networking in some fashion (mostly technical sales of packet analysis solutions) for 20+ years. The thing is - you don't need to be technical to see that products like this are complete snake oil. Literally NO ONE uses them outside of gullible audiophiles. Professional sound studios and engineers don't use them, Hospital ICUs don't use them, Streaming media companies don't use them, high end video conferencing doesn't use them, medical testing companies don't use them, financial trading firms don't use them, etc, etc. What do almost all of these firms/people actually use? Standard enterprise networking gear (Cisco, Arista, etc). I mean if hospital ICUs aren't worried about ethernet "noise" interfering with patient data feeds no one at home needs to worry about their ethernet gear interfering with anything.... and for the few times they are worried they'll use something like this:
Protect patients from harmful leakage currents on Ethernet network lines! You can use this 60601-1 network isolator in patient care vicinities.
www.tripplite.com
The thing is you can buy nice used enterprise networking gear for 100-200 dollars on ebay (I have a 48 port Cisco swtich with 2 10 Gbps ports that I paid like 150 for a few years ago for example) which performs great. I just checked a couple of days ago and my switch hasn't seen a single frame error (not even 1) on any port since the last reboot - which was like 15 months ago. All my cabling is whatever bulk cat5e the builder used when we had our house built.
If someone is really so paranoid about "noise" they should just use fiber, which is cheaper or wifi - which is WAY cheaper. If this problem actually existed (which it doesn't) both of those solutions would be FAR, FAR more effective.