Follow-up question: does the dongle get hot when it's plugged into a powered hub, physically remote from the RasPi, when the hub is plugged into the RasPi's USB port?
If so, we've eliminated the RasPi, the dongle, and the RasPi's USB jack as obvious sources of failure. The list of remaining sources includes voodoo, deep magic, and gremlins.
When you void a product warrany, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.