I think the powered hub is what has got rid of the disconnects. I would have expected the laptop USB 3.0 ports to be up to the job but I guess not. But having the hub means only one cable to connect for 4 devices so it's what I wanted anyway.

Was the laptop was doing power-saving stuffs or do you keep it plugged in?

I turned off the power saving stuff as Graphitone suggested, possibly improved things. Laptop is always plugged in whilst using the adapter.