I' realize this post is old but I thought I would offer another possibility on how to fix it because I had the same problem with the display on my Tab A 8" randomly turning off and it was an easy fix once I realized what was causing it...its the magnet embedded in the case I bought for it. If my tablet lays flat in the case (on the magnet) the display turns off. Lift the tablet an inch or so away from the magnet, press the power button , the display comes back on and resumes resumes its regular display settings. Its that that simple. I can use my tablet and keep it in the same case as long as it's in a trifold position (sideways) without any problems.
I'm having the same problem. It's not the tablet. It has something to do with your wifi. When I am connected at home to my Xfinity wifi and router, it randomly reboots. When I am at a public wifi or a friends house, it doesn't do it. Sorry this is not a solution, but mabye finding out if it's a wifi/router thing, it could help pinpoint the problem