To connect at 450Mbps your wireless clients must also support 450Mbps and the Router's channel bandwidth must be set to Auto 20/40MHz.   For wireless security you must use WPA2 AES for 802.11n support.

Log in to the TEW-691GR by entering https://192.168.10.1 into the address line of your browser.

The default User Name is "admin", without the quotes. There is no password by default. Click "Login"

Click Wireless and then Basic.  You can change the channel bandwidth here.

Click Wireless and then Security. Select WPA2-PSK with AES and define your pre-shared key.