@Mazzie 

Hi,

May I know the model number of your new router as well as the TP-Link extender?

After the setup, may I know which two lights lit up?—can I have some pictures?

Did you set up via WPS button, web UI, or Tether APP?

PS: the instruction to set up via Tether APP: https://www.tp-link.com/support/faq/1373/

Thank you very much and wait for your reply.