Have you just received the box? I thought they were sending everyone Connect Boxes now.
Make sure you’re trying the right password with the right SSID, as I believe the box comes with separate SSIDs and passwords for the 2.4GHz and 5GHz networks.
You can go into the menus and do a Factory Reset, which should take the passwords back to what’s printed underneath in case they sent you a box someone else had used and it wasn’t reset before they sent it out to you.