Buffering

On no! No answers.

I presume you are using a wireless connection. Are you able to use a cable between the TV and the internet connection? This usually improves things.
I have no idea about WiFi boosters, sorry.

An no! The internet cable enters the house upstairs in the bedroom where the computer is. We don't use the computer now, as our DS built it. He no longer lives here. We can't re-site the router either, so I just wondered about a Wi-Fi booster.

Get a pair of datapoints and a length of CAT 5 or 6 cable,
Do not use datapoint on an extension lead.I use datapoint for my workshop PC, nearly 200 feet away from router, and it runs as fast as the PC next to the router

I'd check my broadband speed first, it may just not be fast enough. I may have misunderstood though because I'm not sure what you mean by 4G in your post. If you mean LG TV then I'm not aware that LG call their technology QLED. Perhaps you mean 4K QLED? If you do, have a look at this link:-
recombu.com/digital/article/how-to-stream-4k-video-broadband-speed-wifi

If you meant something else, perhaps you could post again.

My son solved this problem for me by adding an Ethernet cable to the tv. All is now okay. No more buffering.