2020/10/17 12:36:07 ERROR 59 (0x0000003B) Copying File D:\FN_Drobo_Bkup1\Utilities\UNRaid\BKUP\VM\Ubun2\10112020_0405AM_vdisk1.img
An unexpected network error occurred.

I gave up. I simply deleted all the files that were giving this error since they were big files and are backup of VMs within unraid.

There’s been a longer and longer thread here.