USB 3 External Hard Drive Disconnects after a few min

Hi,

I could not find this via the search.

Has anybody come across your USB 3 connected Hard drive just dismounts.
X10
Firmware 2.0.5
4 TB internal Hard Drive
4 TB External Hard Drive in a Self powered enclosure

Tried both USB 2 and 3 connection
after 20 min the drive dismount.

 

It is probably the enclosure which disconnects rather than just spinning down the HDD.

 

conect to PC and search for control panel from manufacturer, should have option to set shutdown timer on the hdd to off

 

Great thanks for the help.