SMB copy still not working well

I'm copying some 60GB from a W10 machine to this W11 machine. Copy speed drops down to 2-3MB/s and then inexplicably increases after a time to about 100MB/s (or better) and then drops away to next to nothing again.

I thought this silliness had been fixed - what should have copied in about 10 minutes is still not complete after some 40 minutes (grrr...)

David

I got my first computer in '92 then after retiring in '94 got a part-time job in a computer store and started building computers. There's always been variable speeds of copying files from one location to another, between different drives. Back in those days it worked when copying floppy disks to create a RAM Disk, store from one disk into it, add files from other disks, clean out what was not wanted then copy back onto clean disks. Basically it's the copying into memory then writing into the destination, does take time and larger files take longer and the speeds do indeed vary, nothing like picking a box off a shelf and putting on another.