You may not need anything extra. When I press the Input button on the remote for my LG 50UK6090PUA - in addition to the expected HDMI1, HDMI2, etc. there is also my server listed. I pick that and navigate to the video I want.
There are plenty of reasons that my case may be different from yours. I am using a WD MyCloud that is running its stock DLNA server and my files are mkv files instead of mp4. Still, it is worth a try and costs nothing in dollars or time.