Depending on what you actually want to do there may be a work-round.
We have a DNS-320 with almost the original firmware that we use to keep service manuals and service details for our clients equipment. All of our site service people have a tablet (samsung galaxy note 10.1) that they use to access that NAS to check and update the notes as necessary. All of this is done using the AndFTP app on the tablets and the FTP server on the NAS. It does require correct setting up of our firewall and strong passwords but other than that it works well.