@0556226253 

Hello,

For the range extender, the password of it is the same with your main router. So you can try your router's password.

If it still not working, please try to set up it again.

This article mainly introduces how to configure the range extender via the web management interface. Please click on this link to get detailed information: 

For Single-band RE:
https://www.tp-link.com/en/support/faq/1411/

For Dual-band RE:
https://www.tp-link.com/en/support/faq/1400/ 
                                                                                                                                                                                                                                                             

NOTE: Please use your home wifi password to configure the range extender.

We suggest you customize the network name for the extender. You can see it in step 3.

May it help nad have a nice day!