My Router Stop Working

I have AN1020-25 Ptcl modem which have the router in it. The problem is this when i change the password of its wifi and try to connect with any device it stop connection.When i connect my computer to wifi it says "Unable To connect" and i have to reset the modem and then the device works fine untill i don't change password or any other settings.

1-Go to the properties of connection: (for example)

2- In Network Security Key, enter the password which you have entered in settings of Wi-Fi.

3-Connect to the Internet. B)

reset your router to factory default setting and re setup it again may fix the problem...