It is strongly recommended to check the on the bottom or back of the unit. Modern units like the often have a unique, randomized password printed there. 2. Security & User Management Review

Changing passwords is just one part of security. Here are three extra tips to keep your ZTE F6640 safe:

Some ISPs change the default password to a custom string (e.g., multipro or Web@0063 ).

There is often a "non-admin" user account by default which limits what you can configure (e.g., restricted LAN/Ethernet settings).

If you are certain you are typing the right password but still getting a "Login Failed" error, try these fixes:

If you are locked out, locate the physical Reset button on the router. Press and hold it for ~10 seconds to restore factory defaults. ZTE ZXHN F6640 ONT | Configuration & Interface Walkthrough ZTE ZXHN F6640 ONT | Configuration & Interface Walkthrough YouTube·IT Solution Drinia

Whether you are trying to access the admin panel to change your Wi-Fi name, you’ve forgotten your login credentials, or you simply want to boot unknown devices off your network, understanding how the F6640 handles passwords is essential.

Look for an option related to "Change Password" or "Admin Password."

Once reset, you can log in with the default admin credentials mentioned above.

Click Apply or Submit . Your devices will disconnect and require the new password to reconnect. Changing the Admin (Login) Password