@Stephen33 

Do you mean the WiFi password? (By the way, the default web management UI password is admin if you actually talked about this one.)

If yes, I think you could reset it and set it up again via Tether APP or web UI maybe, not via WPS button since I heard that it could change the router's password and randomly generate a new one. Or if you have a wired laptop, you could connect it via cable to RE450 and log into http://tplinkrepeater.net and the default password should be admin.

https://www.tp-link.com/en/support/faq/1398/

  @Heidi_Alp Thanks for your response but (I should have mentioned) I have already tried “admin”.  I think I’ll give up but thanks anyway.

Heidi_Alp wrote

  @Stephen33 

Do you mean the WiFi password? (By the way, the default web management UI password is admin if you actually talked about this one.)

If yes, I think you could reset it and set it up again via Tether APP or web UI maybe, not via WPS button since I heard that it could change the router's password and randomly generate a new one. Or if you have a wired laptop, you could connect it via cable to RE450 and log into http://tplinkrepeater.net and the default password should be admin.

https://www.tp-link.com/en/support/faq/1398/