Originally Posted by TheVoid:
“So the hub is in the hall. I get 80% signal in the lounge right next to it, 50% in the conservatory, but 100% upstairs?!
What's the best settings to improve the Wi-Fi please as this appears odd to me.”
There is likely only one parameter you can change, the WiFi channel being used.
What is probably causing the signal differences is a combination of building construction and interference. Different materials used in the walls and ceilings will attenuate the signal in different ways and the more walls etc the signal has to go through the lower the resulting signal will be.
So it is not in the least bit surprising or odd that you get wildly different signal levels in different rooms. Not much you can do about attenuation through walls and ceilings other than do a bit of DIY with a sledgehammer to remove the obstruction

Or more practically move the HomeHub to improve signal transmission in certain areas but perhaps at the expense of signal in other areas. In some cases it doesn't need much movement to make a big difference.
If interference, often from neighbouring WiFi networks, is an issue then changing channel might help, if there is a clearer one to switch to of course.