@Mags12 

Good day,

Thank you very much for your time and patience.

Sorry for the delay.

Is your model number RE200, or RE220?

If you use the mobile phone to connect the extender, would you have the same error message?

Did you set up extender via WPS button?

If yes, please try to reset the extender, and configure it again via Tether App or web interface;

https://www.tp-link.com/support/faq/1373/

If you already set up via Tether or Web UI, please fetch a computer and connect it via Ethernet cable to RE200;

Then log in the web UI via http://tplinkrepeater.net ;

After that, go to settings>wireless>host network to check the Wi-Fi password;

Thanks a lot.

@Mags12 

Good day,

Thank you very much for your kind reply.

So after the setup, the 2.4ghz and 5ghz would all lit up and it just said invalid password when try to connect right?

Have you got a wired laptop so that you could log into RE200 and check what the password is?

(And if there is no Ethernet device, please help do the following test:

During the setup, only input the correct password for one band, such as 2.4ghz, then use 12345678 as the password of the 5ghz;

After that set up, only the 2.4ghz lit up, then use password 12345678 to connect the 5ghz and check what is the password for 2.4ghz;)

By the way, are there any special characters, like #, $,* in the home router’s password?

Did all the mobile devices have the same issue when connecting to the RE200, or just the TV firestick;

Thanks a lot.