I use the Synology DS218+ along with two 4TB WD Red drives (which I got off craigslist for a steep discount -- the seller even let me run diagnostics on them fo

I use the Synology DS218+ along with two 4TB WD Red drives (which I got off craigslist for a steep discount -- the seller even let me run diagnostics on them for me and they were very lightly used). I don't have to pay for the software. If you stick with the Synology OS it comes with they have a package manager with things like various media servers, Cloud Station, a download client, etc. You can also just shell into it and install your own stuff. You can get NAS disk stations with more capacity (more drive bays), but this was all I needed.