How do I upgrade the firmware on the RE220 extender?

You can upgrade online by logging into http://tplinkrepeater.net, going to Settings > System Tools > Firmware Upgrade, and clicking CHECK FOR UPGRADE. For a local upgrade, download the latest firmware from www.tp-link.com, then click BROWSE to locate the file and click UPGRADE. Do NOT power off the extender during the firmware upgrade process, and make sure you have a stable wired connection between the extender and your computer. (Page 44)