I had a more detailed look on to the logs.
The entries with the MAC as name are from the hostap, if a WiFi connect was made. I use WPA without Enterprise. I thought Radius request would only be made with Enterprise – but this is wrong. Therefor I found those entries in the Accounting. There does not exist a switch that allows to turn of the Radius for WiFi.
I also had a mistake in my accounting class (post paid instead of pre paid). Now everything seems to work
Regards,
Michael