@Bex9 depending on whst smart plugs you have they may be having issues connecting tomthe default dualband SSID Sky hubs use. In these cases you need to split the two bands which is explained here Split Sky WiFi bands which works on the black Sky hubs but not the new white Wifi Max type.
Loss of internet connection overnight can be down to maintanance of the supply network which is unavoidable most smart home systems can cope with only a local network connection as no ISP can guarantee a 24/7 connection. I would expect work to stop over the holiday period.
Another possibility is that you have Sky Q tv boxes and those boxes are set to use the eco standby mode which saves power by turning off the wifi hot spots so any devices using that service lose connection, the solution is to change each box's standby settings to Active or None.
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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
