@Bell5 thexweak security message is not to do with thecsignal strength of your WiFi. If it is an iPhone or other iis device you can saley ignore the message as it is Apple assuming everyone will throw away perfectly secure Wi`fi kit using WPA2-PSK and buy new kit that supports WPA3 oh and probably replacecolder devices that wint connect to WPA3. Sky hubs are secure using their default settings.
Poor WiFi on different floors is very common you mention a booster which could be part of the problem if it is installed in the wrong place. Boosters can only offercwifi speeds half as fast as the connection from the hub to the booster. Therefore it is vital the booster is sited correctly which in your home is likely to be in the hall or landing onnthe lower floor.
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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
