can’t connect to -ext WiFi because it says password incorrect

I first tried setting up by going to re.rockspace.local, but when I got to the extend page, entered the router password and clicked the extend button, it took 5 minutes and still didn’t succeed, so I tried method 2 on the set up manual and pressed the wps button on both the router and the extender (AC750). After it succeeded in extending and the extender WiFi name changed to the WiFi router name + ext, I tried connecting my device to the extender by typing in the same password as the router, but it keeps saying it is the incorrect password.