I just got a new company notebook and hat exactly the same issues. My problem was that I used WPA with TKIP instead WPA2 with AES as mentioned here:
Solve an issue where an 802.11n WLAN shows only a 54 Mbit/s datarate
I just got a new company notebook and hat exactly the same issues. My problem was that I used WPA with TKIP instead WPA2 with AES as mentioned here:
Solve an issue where an 802.11n WLAN shows only a 54 Mbit/s datarate