Using NAS to stream files rusing UPnP equires two things, one hardware, one software. You need the hardware ro be or act as a server. You also need UPnP server software loaded on the server device.
The Buffalo hardware is described as an 8TB NAS so is basically what you want. However the UPnP server software to run on it needs urther consideration. dCS recommend a specific piece of software which is MinimServer ( now MinimServer2). The reason why is here:
An issue is that MinimServer is written for certain brands of server unit and Buffalo is not amongst them:
If you use other types of server software then the result can be unpredictable. I have tried using Twonky and the result was , well, horrid, with missing repertoire and wrong metadata being supplied. Having two or more albums with the same title ( common for classical genre) confused it. It kind of worked, sometimes.
However there is light at the end of the tunnel. Firstly Melco is a division of Buffalo and it might be that the Melco software is compatible or there may be some other combination. You can ask here for suggestions:
https://forum.minimserver.com/forumdisplay.php?fid=12
Although dCS only recommend MinimServer some other contributors to this forum have posted that Asset UPnP DLNA may also work OK. I haven’t tried so I am just relaying the opinion.