The following
Check whether the Teufel WiFi Link USB Adapter is correctly connected to the USB port of the AV receiver IP 8000. Remove any USB extension that may be used and check whether it is possible to establish a connection.
Check if the entered security key is correct.
Check whether a Mac address filter is active in the WIFI base station (AP) and, if necessary, enter the MAC address of the IP8000 as an exception in this filter.
Make sure that the WIFI function is switched on at the WIFI base station.