Windows 8.1 and AVM FRITZ! WLAN USB Stick AC 430 a bad combination

Have 2 days despite intensive try not manage the WLAN USB stick on Windows to get 8.1 to run.
The phone support was not available at different times.
The drivers seem to be more severely flawed. Sometimes the wireless connection is optimal, then seconds later there is no wireless connection more.
My laptop I have tested for test purposes in the same room at the same time had to go through no wireless problems.