"So it appears the node goes offline only when I connect to it after a few minutes (via Sparrow Wallet). Can it be because it is overheating, connecting to the node actually makes it run hotter?!? I bought the unit couple years ago and I just cleaned it so it shouldn't overheat? The fan is on Auto as well."

You are not the only one, I am having the exact same issue. My node runs fine until I connect remotely to Sparrow, after which it randomly shut down in minutes or hours.