You need a DLNA server software package. People argue a lot over the merits of the many different DLNA servers. Some Buffalo NAS devices include a DLNA server or can have it added.
People have often found that many DLNA clients (like those in TVs) cannot play all of the different types of audio and video encodings. That might be the problem you're having. Often one has to choose between using a DLNA server which does transcoding on-the-fly or manually reencoding existing recordings to a diffenent format.
Alternatively, you can get a small-form-factor computer, connect it to the network and plug its HDMI output directly into the TV.
Marantz SR7009 avr + MM9000 amp --> Atmos 7.1.4
Fronts=NHT 2.9+AC2, FH+TM=DefTech PM1000, LCR+TM amped