For many firmware versions of the DN81R, there is no permanent default password. Upon the very first boot, the system will prompt you to "activate" it by creating a strong password of your own. If you are looking for a default because you are locked out, it is likely that a custom password was set during this initial setup. How to Recover or Reset a Forgotten Password

: On the login screen of the DVR itself, click the "Forgot Password" or "Double-Click" in the bottom-left corner of the login box. This often brings up a Security Question prompt or a GUID/QR Code used for remote resetting via the mobile app.