Windows to Android file transfer -- aborts after a minute or two

I have a Win11 Dell Laptop and a recent (last 12 months) Sony Xperia Android phone.

I connect them via a USB-C to USB-C cable and select File transfer on the phone.

I use Windows Explorer to do the copy operation.

I try to copy, say, 1GB of music files. It runs for a few minutes and terminates with no message. I cut it to half a gig. Same thing. Quarter gig, same thing.

I have about 200GB to transfer.

The destination of the transfer is the SD card in the phone.

What is suggested?

Addition:If I make the copy in really small chunks, and keep playing with the phone so it does not sleep, it appears the copy completes.

In the phone settings, I do not see a way to prevent it sleeping.

What to do?