Nokia 5.1 - problem moving files by USB

I was transferring music to my mobile phone and photos from my phone via USB.  The connection stuck very soon.  In the past, I have been successful with Nokia 5.
I also tried to transfer with a Linux machine. Then I noticed that the connection was lost while dimming the screen.
So, I changed the display sleep time to 30 minutes.  After that the transfer worked without any problems on Linux and on Windows.