|Bear in mind that the password to connect to the router management interface is different than the password to connect a device to the router.|
You need to connect to the management interface first then set up wi-fi passwords once you are in.
If you have forgotten either one, the solution is the same. Reset and start again. Very few manufactures give a default password for the wi-fi connection as the format will differ depending on the encryption method used. That needs to be set by the user.