Thank you very much for posting Matthew.
We understand that you have some questions on regards to the Intel® Centrino® Advanced-N 6200.
On regards to the description of your issue we would like to know if the wireless adapter came installed on your computer from factory just to make sure that you will not ran into integration issues. We would like to know also if you are using AES Encryption only.
Also, we would recommend you contacting your router manufacturer to download the latest firmware version, or get information on particular models supporting High Throughput.
You may also disable packet bursting or similar features on the router and configure the router wireless profile to use Wi-Fi Protected Access* (WPA2-AES or WPA2-TKIP).
You may also check the following link for further reference:
Intel WiFi Products: Data rate will not exceed 54 Mbps when WEP or TKIP encryption is configured.
I hope this helps