You really need to get it to either a Bosch Autocentre, Main Dealer or other specialist with the right tools. Not all ODB2 scanners will talk to the transmission system controllers. A code read will be needed to help diagnose which part of the system is unhappy.
It sounds temperature related so it’s also worth checking the transmission fluid level and it’s colour whether it smells burnt. If it is very dark and does smell burnt then sadly I suspect that if you are losing drive then the gearbox is about to fail. Low fluid level causes a loss of pressure in the gearbox and that is that, although it jay take a week or two. A torque converter issue can also result in damage. Anything causing pressure loss means the clutches slip, wearing them out quickly. It could be a solenoid as well, but limiting use is key to avoid critical damage that needs a rebuilt box. That comes with a bill of around £2k.
My ‘05 box failed with no warning at all. One minute is was fine and then it sounded like a bag of spanner’s. No warning light either.
