I have set the hub to from 2.5/5 ghz our alarm and solar panel system will only support 2.5ghz, we are fibre optic to the premises we have all had our installation at different dates over the last 8 months, it was poor before the fibre optic it is hit and miss now. The speed to the hub is excellent, the speed from the hub is slow and unreliable, BT only guarantee the speed to the hub, after that you are on your own.
Do you find it slow in every room?
What speed are you getting after the hub vis an ethernet cable and wireless – you will need to do a speedtest for this. Any sppedtest supplier will do. Restart the router and carry out another test. Is their any difference?
If you have the smart hub 2 router, it is widely known to have a glitch that disrupts the connection between certain Wi-Fi enabled devices. I did however believe this was fixed sometime ago!
What hub do you have?