Several months ago, I decided to replace my network storage device with a standard external hard drive that hooked up to the USB connection on my Linksys EA3500 SMART WiFi Wireless Router. The external hard drive I started out with was the Seagate Expansion 3TB Desktop External Hard Drive USB 3.0 (STBV3000100). I used that for a couple months until it became corrupted. I was able to restore it by hooking it into my Windows Vista desktop and running a restore function; however, several of the files were missing. I thought it might just be a fluke because the hard drive ran fine after that; however, a couple weeks later it got corrupted again.
I proceeded to get another external hard drive. I reasoned that maybe I had an issue with the hard drive getting too hot or something, and I still trusted Seagate so I got their desktop model. The Seagate Backup Plus 3TB Desktop External Hard Drive USB 3.0 (STCA3000101) fared better than the first drive I got. It never got completely corrupted; however, from time to time I noticed that some of my files seemed to be missing. More obviously I noticed that a couple files now and again got converted into empty folders. For example a photo that had been named "552.JPG" retained it's name, but now it is an empty folder. Out of a folder with 331 files, this happened to 6 of the files. 5 of the files were .jpg and one was an .mp4. That frequency of corruption seems to generally hold true in other folders as well, though some pass unscathed.
Since I already replaced the hard drive, I'm thinking it's potentially an issue with the router. For your information the router's firmware version is 1.1.39.145204. It appears that someone else on your forum has already had a similar issue and it was also with a LinkSys router, which looks to possibly be a similar model to my own. Unfortunately, no one was able to really solve his issue, and thus I feel a need to post my issue. If you want to see the related post, you can look here: Files turned into folders on external hard drive
Update June 26, 2014: Okay. So I've run a file recovery program named Recuva on the hard drive. I had it search for "non-deleted files (for recovery from damaged or reformatted discs)" and then I had it copy everything it found onto a fresh hard drive. The end result was that it found 277,103 files which totaled 928GB of data. It seems the missing files were in some kind of limbo that Recuva was able to find. The files don't appear to be damaged they were just dislocated or something. Recuva even recovered the folder structure for most of them. The one folder structure it didn't recover was one I named 2013 (which contained all the photos and videos from 2013). My 2013 folder had mysteriously disappeared, but Recuva seemed to recover most of the files including the sub folders, but it wasn't able to figure out that they had been in a folder called "2013", it just had a question mark for the main folder.