FWIW I have a Buffalo Linkstation, and while it works great as a NAS, large parts of its extra functionality just don't seem to work e.g. the media server.
I wasted a day on it and then left it. A lot of stuff on the net about the issues...
Any NAS with an HTTP server should be web accessible. You need to open up Port 80 in the router, set up some reasonable login security in the NAS device (because the open port 80 means it will be attacked with dictionary attacks within days if not hours), and then arrange for a fixed IP to be directed to the device (and there are multiple ways to do that, with a straight fixed IP from the ISP being a simple solution).