Problems with automatic transmission

Hello.

I have a question, if this is the way out of the forum

similar to my Audi A8.

Data: Audi A8 4.2l Q Year of construction 1996

My automatic transmission switches at approx. 50Km/h no more(speed goes up, but nothing happens),

when I then turn off the dare and start again everything goes again Perfect until approx. 50Km/H,

I'm gonna go check on Oel tomorrow,

Maybe someone has a tip?? Control unit?


Mfg Patrick