USB file copy problem

I have not posted here in ages as all has been going very well. Now I
finally have a question.


I have an Android phone LG-6 that I back up to my main computer on
occasion. The file copy is extremely slow and just yesterday noticed the
operation stops or does not take place at all on nested folders just two
or three deep.

I have tried both USB-2 and USB-3 ports with the results.


The machine dual boots Win10 and Ubuntu 18.04 and has the same problem
with both operating systems , so I know it's the hardware.

The problem is only evident when I try to backup my phone, no problem
with an external HD.


Since I have five machines in my house that are used frequently I tried
them all and the file copy works fine on two of the machines.


One of them is the newest machine in the house (win10) and the other
one, the oldest (win7).

I'm a bit stumped. Any ideas?