how cool you're keeping the miner/room, and some luck. To troubleshoot, I always first reboot the miner and keep an eye on it. If it can't hold the freq that it used to be able to handle, then I try to figure out what changed. In all of my similar situations, the change was always the temperature in the room (one time I moved a miner to a hotter location, another time the A/C went out). Once I got the miner back to the same room temperature conditions it was in before, it worked like before. These boxes are a little finicky at the higher freq.
Yep, doesn't make sense to me because they never go above 70c. yet when they do die it's only during the hottest part of the day despite regardless of fan setting.