TL;DR: Correction: disabling the AppleThunderboltNHI.kext driver WORKED for me! Yes, I've had the sporadic shutdown problems, sometimes occuring very frequently (like every 3-5 minutes), essentially making my MBP mid-2014 unusable. I was skeptical, but disabling the Thunderbolt ethernet driver really works -- I have not had shutdowns for months since I did this. Then I updated to the latest version of Mojave and the update process reenabled the driver, and I immediately had several sequential shutdowns. So I disabled it again and back to a well-running mac. It is a bummer to not be able to use hardwired ethernet, as I liked doing that when in the office. But it is not a serious enough drawback to cause me to get a new mac. I am hoping that my whole logic board is not in the process of degenerating, as some previous posts have suggested might be happening.