Do you mean the Restart button on top of hub - or is Reset different?
OK I found the reset button. After I pressed it the colours of the light started changing. Now it's gone back to blue again. My tablet is connected to the hub at the moment.
I've just restarted the tablet and it was showing "connected" right from the start.
It looks like you have solved my problem, Richard. I'm very grateful to you. Thank you.