Please connect an Ethernet cable from your existing modem/router/network in to the port labelled "Internet/WAN" on the back of the TP-Link.
You will be prompted to log-in. The default username is "admin" and the password is "admin" (unless you have changed these prior).
Click "Firmware Upgrade" on the left menu.
Click "Upgrade" and press "OK" to confirm. The upgrade process will now begin and take up to 5 minutes to complete.