Auto gearbox is not changing between gears as should when the car is cold but after 1min works fine

tiptronic auto gearbox is not changing as should while the car is cold but after 1min the gearbox works fine what could be the fult

sounds like the transmission...

I doubt it's the problem but make sure you have the right transmission fluid. Fluid with a heavier viscosity would require time to warm up to operational temperature.

There are so many variations of the tiptronic system, you need a manual or troubleshooting guids for your specific system.