If you are using the BT supplied HomeHub 5 VSDL WiFi Router then I suggest changing a couple of settings to get the most of it.
First in your Browser (I normally use Google Chrome, but seem to work with Edge and FireFox) go to:-
And you should see, click on Advanced Settings:-
And you see:-
Scroll to the bottom and enter your password (see card on the back of the HomeHub for this and click OK:-
And you will see the screen, click "continue to Advanced Settings":-
Then click "Wireless":-
Then click "5 Ghz Wireless":-
Then change "Sync with 2.4Ghz" to No and click Apply:-
Also in Advanced Settings I turn off:-
"Home Network" -> "Smart Setup" -> "Enable Smart Setup:" - No - Click Apply.