so I have noticed SEVERAL threads about the 'out of service area' error people have been getting and I haven't seen any resolution, and I recently experienced it myself. After 2 days of tinkering, I found the reason and resolution. After updating to 4.4.2 via LG FlashTool (I was rooted and even after full unroot and master reset AT&T still wouldn't let me OTA) I was only getting 4G and not LTE like in 4.1.2. So I fixed that in the hidden service menu 3845#*980# and forced LTE. Everything was working great until I got the dreaded out of service area error. Not thinking about what I did 2 days ago, I called AT&T thinking it was a network error. I replaced the sim and was about to do a warranty exchange when it dawned on me that I had forced the LTE. After switching back to Automatic, everything was back to normal except I'm only getting 4G. So for anyone having this error, I have attached some screenshots of how I fixed it and hopefully it will help you too! NOTE: If you have a variant of the AT&T version, eg: 988, make sure you enter 3845#*988# in the dial pad or it won't come up!
EDIT: I have also noticed a great increase in battery life as well!