maybe the Pi 4 would be able to do this with a USB attached disk box, but you'd be much better off with something like a commercial NAS - and I say this as some

maybe the Pi 4 would be able to do this with a USB attached disk box, but you'd be much better off with something like a commercial NAS - and I say this as someone who has used ARM boards since the Sheevaplug. It all depends - do you want a fileserver or a crash course in how to build a fileserver?