I had previously an ancient Fritz WLAN stick, so I had 3 Mbit / s. Then I have a mini WLAN stick of CSL worried me with antenna, so I had an average of 12 Mbit / s. Still not enough for DSL16000.
With this antenna I now consistently 54 Mbit / s! The signal strength is at 5 of beams, vorhher there were 3 to 4. The Fritzbox is 1 concrete wall, 1 wooden door and 9m as the crow flies.