On the left menu, go to System Tools > Firmware Upgrade .
The good news? Updating the firmware is free, takes about 10 minutes, and can feel like getting a brand-new router. tp link router firmware update tl-wr840n
Open a web browser and type: 192.168.0.1 or tplinklogin.net . Username: admin (usually). Password: admin (or whatever you changed it to). On the left menu, go to System Tools > Firmware Upgrade