Using a hard drive for FTP access on an access point?

Hi, I have a couple of routers being used as access points in the house and they both have USB ports and a functionality to support FTP. Which would be useful if I wanted to access the odd document remotely. I know NAS drives do it better but they are very expensive. So my plan is to get hold of a basic usb hard drive and connect it to one the access points. Can this way of connecting support FTP or does FTP connected drive have to be connected to the main router? Thanks, Wayne

If the APs all have USB ports for FTP, I don't see why the devices wouldn't be able to access the external HDDs plugged into them. You could connect an USB flash drive to test just to make sure it works before purchasing USB HDDs.