I made a previous post about this topic but those routers are no longer what im looking for.
Background info: 3 computer 2 wireless 1 wired.

We are getting a new router and wanted to connect an External Harddrive to the router so that all of the computers can use the drive to backup/store/w.e they want. I went to bestbuy the guy said that i need a router that has a USB port to connect the drive. I searched on Newegg and found some routers that have a USB port, but then i noticed some adapters that allow a user to connect 2 harddrives to the adapter and the adpater turns the connection into a RJ-45 type connection to connect the router.

The question is. i heard i may have to use FTP or a VPN to transfer files but what type of VPN will i have to use?
IPsec, PPTP, LT2P or VPN Pass through?