The temperature was set too low.
Increase the cooking temperature by 10–20 °C.
The food has a crust that is too thin and too soft.
Increase the cooking temperature by 10–20 °C.
Extend the cooking duration.
Switch on the Crisp function.
When cooking moist food such as frozen chips, follow the instructions on the packaging and turn the food more often to reduce the moisture in the oven compartment.
Open the appliance door 2 to 3 times during cooking if there is a lot of food or if the food is very moist.
Do not add a burst of steam at the end of the cooking process so that a thicker crust can form.