@Graham+Denyer you need a good steady wifi signal to stream video which sounds like whatever device you are using is not getting. WiFi signal strength is affected bybthe lsyout and type of construction of your home so isnt possible for Sky or any isp to promise you will have decent wifi in every room with only the basic free wifi router they give you. Ideally you would use ethernet canles to stream video as they not only provide the best bandwidth they are also immune from interference.
Failing that assuming your hub and streaming device are out in the open and above obvious obstructions like radiators its down to either buying Sky's add-on WiFi Max https://www.sky.com/help/articles/sky-wifi-max or buying third party kit which can work out cheaper in the long run.
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65inch Sky Glass, 3 Sky Streaming Pucks, Sky Ultrafast + and Sky SR213(white Wifi Max hub) main Wifi from 3 TP-Link Deco M4 units in access point mode
