What is your broadband speed and how is the tv connected to the Internet, an ethernet cable is the best option and is more stable than a wifi connection also how many devices do you have connected to the Internet, sky say that to watch hd channels you need a minimum of 25mps and for uhd a minimum of 35mps, you can check what speed your tv is getting by opening the Netflix app going to get help opening that and going to check my network and run that
P c marlow
