LOL. "science-is-truth" sent me a private message stating that i was simply incorrect and there was no way this CableMatters adapter could actually perform the claims I (and others here) have made about it. He insists that because he worked for Bob Metcalf, it's not possible that an ethernet-to-usb adapter would be able to provide enough bandwidth for the LG tv to provide a substantively better ability to stream UHD 4k content locally for plex users.
To be 100% clear: "science is truth" is completely wrong here, and is attempting to use an "appeal to authority" argument to bolster his case. His authority has no bearing here, and his position is trivially shown to be false purely by demonstration. I, and several others in this thread, have actually gone and tried this adapter. I have trivially measured hte bandwidth between the TV and my plex server, using both the built-in ethernet and the adapter. i can easily see how the built-in ethernet is 100mbps, and how that immediately and deleteriously impacts content that needs to go above that (for example, i have content that can easily go >200mbps in some places). I can then easily see that over the adapter, hitting those speed is not at all a problem.
This is, of course, unsurprising. That same content worked fine over the *very same* usb port when plugging a usb key. So, of course there's enough bandwidth over that port to be able to handle that content. What's fortunate is that the LG tv accepts the adapter plugged in there.
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Note: i've been using this system for several weeks now. It's been flawless. Zero issues streaming *any* media from my plex server. Zero issues with any other streaming apps on the TV. If anyone is running into the same problem with 100mb/s not being enough to stream some very high-bandwidth content, then def try this out. It's fantastic, regardless of what ignorant people like science-is-truth say.
Cheers, and thanks again to KM Lee for discovering this and letting us all know. In one simple step this has solved literally the biggest and most annoying issue i've had with this TV.