I have an automatic A5 Black Edition 2014.

When I first start the car drive a short distance around a 1/4 mile gears change okay. Following this it bleeps showing a R with a cross through it and an exclamation mark in yellow appears on dash. The gears then only change from 1st to 3rd and won't engage into any other gears including a reverse.

Once the engine is turned off and restarted the gears will engage, but then the same will happen again (as above).

Could anyone advise, please. Thank you in advance.