1. Set different SSID for 2.4 & 5GHz. In notebook choose the SSID for 5GHz.
2. Use WPA2-PSK/AES encryption.
3. Set 5GHz country to USA.
4. Test with a speed test web site first, and move the notebook to a place in a direct line of sight with the A2004NS. If behind a wall, check whether 2.4GHz yields better throughput than 5GHz.