Cannot copy large files. Starst then stops. Win 10x64 1803

Hi,

This 9020 small has been great up until now. Have had several USBs plugged in to various ports back and front and up until it seemed all worked with large avi files.

Now I buy a new 2TB and place it in a Simplecom ext box and I find I cannot copy to it from another same box. I go further after much testing and see it will not do it to/from any drive.

As the Simplecom is USB 3 I had both drives plugged into the back USB3 ports in my tests. I also tried other drives in the other ports and noting works. All started copying then stops.

During my many tests I ended up messing up a drive in one of the ext boxes and had to find then partition and in doing so lost some files, so not too happy about that !

This morning I turned the box on and decided to plug both ext drives into the front USB 2 ports. and tryn to copy a 78GB file.  Now I see it working! and is nearly finished.

The new 2TB drive was always fine as were the others but it seems it is maybe some of the back USB ports especially the USB 3 ones.

In my tests I checked for drivers, uninstalled them from Dev Mgr etc, checked with Dell Assistant and other driver programs yet nothing came up that any drivers were missing.

Any help here please about what this problem may be.

Many thanks

oz