To update the VRP software of an AR2200 router, the administrator can use FTP or TFTP as the methods of transfer. The AR2200 router can act as an FTP client to transfer the VRP software and similarly can function as an FTP server to facilitate the transfer. Additionally, the AR2200 can also operate as a TFTP client to transfer the software. However, the option of the AR2200 router acting as a TFTP server is not viable in this context, as typically routers are set as clients in such configurations while updating software.