Wow! Very interesting post. At least to you and I since we both seem to have a very similar problem. Your post inspired me to, finally, check the connection speed of an LG TV which I have in my basement and is only about 10-15 feet from my router. For a long time I've had a problem where, after a while, the video on my TV will freeze and a rotating circle will appear on the screen for several seconds, then the screen will go black, and then the video will resume. This happens almost every time I am using this TV, maybe every time. I've had no idea what the problem might be, but I did not even consider internet speed because I have two other LG TVs, both further away from the router which do not have the problem. I did a speed check on the basement TV and got 17Mbps. I did the same test on the LG TV in the kitchen, about 25 to 30 feet from the router, and got 67Mbps.
I have attached a photo showing all of the details of the basement TV.
I hope you find this info useful. But I am not sure what I might do about it. I suppose I will make one call to LG support. But I expect I will be told that the TV is out of warranty. In any event thanks for your post. I learned something interesting.
Good Luck, Bob