@Catherine9 how are you measuring speeds. If it is over wifi in a room far from the hub the issue is poor wifi signal. In the same room as the hub you should see at least 600Mb/s or the full 900Mb/s if you have the white Sky hub.
You may need better wifi kit if you want faster speeds in every room but as speeds depend on the layout and whether you have solid internal walls excatly what you need will vary.
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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
