In my case, I'm not using WPS. My Model EX6100 extender has a solid green light connection to router, but even after rebooting the iPad (iOS 9.3) and the extender (current firmware) it keeps reporting "incorrect password." I know for certain that my password is correct. This problem occurred after I was connected and used the web interface to change the extender security from WPA+WPA2 AES to just plain WPA2. This is the case for both bands (2.4 GHz & 5 GHz). And yes, the iPad is set to WPA2 as well. So it seems to have something to do with the designation of the security protocol.