Hi Mr Moley
This sometimes is common with the 4000T, it turns the hard drive on between 4 and 5 am to check for updates and stays on for about an hour. If the hard drive don’t turn off by late morning, then take it out of standby then but it back into standby if you want to.
Or just turn off the 4000T at the mains for a couple of minutes, you do not need to turn the hub off if it still connects to the internet OK, It nothing to with the hub unless you have got a faulty hub.
I have the 4000T and mine sometimes does the same, it is not faulty it sometime just forgets to switch off due to software glitch.