@AndrewTHG if you have the newer white Sky hub third party extenders should connect but can cause interference. If your extenders is an older unit try reducing the WiFi security of the hub from WPA3-T to WPA2 in the advanced settings for the unit in the My Sky app.
A better solution is to either buy Sky's WiFi Max bundle see https://www.sky.com/help/articles/sky-wifi-max or to turn off the Sky hubs wifi and use a third party whole home wifi solution.
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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
