Difficulties Setting Up Plex to see NAS

Hey folks,

I've been using Ubuntu off and on ever since Dapper Drake but there's always something that simply doesn't work, which pushes me back to OSX/Windows. There have been a ton of improvements over the years and a lot more things work out of the box, which is great. However, one thing that I've been struggling with recently, is getting Plex Media Server to work.

Hardware:
Intel NUC 3rd Generation Core i3 Mini-PC
Netgear Nighthawk 1900 Router
WD Elements 500gb Portable HD

Software:
Ubuntu 16.04 LTS Desktop 64-bit
Plex Media Server 64-bit (Version 0.9.16.6.1993-5089475)

I'm able to install Plex without any difficulty but I'm unable to browse to any of my media folders. I currently have all of my media stored on the WD Elements HD, coected to my Nighthawk router via USB 3.0. The computer I'm ruing Plex on is the Intel NUC and it's coected to the Nighthawk wirelessly (I plan to coect hard-wired once I can drill some holes and run etheet).

I've done my due diligence with google searches and forum searches, but the scenarios are either different than my own setup, or the solutions are above my head and I don't know what to replace in the fstab edits. I've tried adding the plex user to the computer's admin usergroup, as well as vice-versa.

Any assistance or insight would be greatly appreciated.

Thanks,
Rob