Security Restrictions - Wireless N Draft
The most likely cause of this issue is due to the security configuration set for accessing the wireless network.
Excerpt from Intel support..
Symptom(s):
Client device's Wi-Fi data rate will not exceed 54 Mbps when Wired Equivalent Privacy (WEP) or Temporal Key Integrity Protocol (TKIP) encryption is configured.
Cause:
The IEEE* 802.11n Draft prohibits using High Throughput with WEP or TKIP as the unicast cipher. If you use these encryption methods (e.g. WEP, WPA-TKIP), your data rate will drop to 54 Mbps. Newer Intel® wireless adapter client drivers connect using a legacy IEEE 802.11g connection rather than failing to connect altogether, which complies with the IEEE 802.11n draft.
Solution:
Contact your Wi-Fi access point (AP) or router manufacturer to download the latest firmware version, or to obtain information on particular models supporting High Throughput.
Disable 'packet bursting' or similar feature that may be enabled on the AP or router.
Configure the Wi-Fi client device's profile to use Wi-Fi Protected Access* (WPA2-AES or WPA2-TKIP). You may also choose to configure an unsecured profile, but this option is NOT recommended.
Configure the AP or router to match the client profile.