This happened to me on the same grill as you, This thing was running like a swiss watch for 2 years, then i get a new WiFi access point so i have a better connection for my grill. I wipe out the my old WiFi name, link up the new WiFi to the grill, it does it's update gives me newest firmware (02-02-03 i think) and BAM, this thing shuts off 4 times in a 4 hour time period. I KNOW FOR A FACT it's the firmware because I have owned the grill for 2 year and when i called Trager the said "don't worry your cover because your grill is only 2 days old"
??? WHAT???
So they had me go thru some steps and THEY determined that my power switch is bad (bullsh!t). I installed the new switch and ran it for 3-4 hours never shut off BUT>>>>>> I lost control of the grill via the app, wouldn't do anything temp up/down, shut down, nothing. I still don't trust this thing, now that the new firmware is on it. Traeger has turned something that was fun and enjoyable for me to do in to i'm a mechanic and replacing parts on a 2 year old grill that was working just fine until they had and go finger F the firmware and make this thing a useful boobs on a bull.
Might be time to wheel this thing to the end of the curb and buy something better
man i'm DISAPOINTED.