@Deesine
Generally, we suggest connecting all the extenders/repeaters to the router for better performance.
Customers can also connect one repeater to another repeater which already gets connected to the router, however we don’t recommend you to add more than two repeaters to one single link chain in consideration of the Wi-Fi quality.
For the configuration, please use web interface or Tether App to configure the second extender, the steps are the same as the first extender, but please select the first extender as the host Wi-Fi network when configuring the second extender.
Note: If the first extender shares the same Wi-Fi name and password as your router, the second router might connect to your router as well if it still receive enough signal from the router, so if you would like to connect it to first extender, it is recommended to set different wireless network names on the first extender.