@kosymodo
Hi, please try to download the latest firmware from our official website. https://static.tp-link.com/res/down/soft/Archer_D9_v1_150826.zip
Then, please connect your PC and the router Archer D9 by cable, log into the ADSL Modem Router by typing http://192.168.1.1 /tplinkmodem.net in the address bar of the web browser (such as Internet Explorer, Firefox). The User Name and Password are both admin unless you have changed it.
Please go to Advanced-System Tools-Firmware Upgrade, click the Choose File button and choose the firmware you already extracted in the folder, then press Upgrade.
If you still can't upgrade it successfully, please send us the screenshot of the error to check.
Look forward to your reply.