Once you get the exclusive password, you might disable TR-069 (the ISP's remote management protocol). If you do this incorrectly, the ISP cannot push firmware updates, and your line might be flagged as "hacked," potentially leading to automated throttling.
If you have tried every password in Part 2 and none work, the ISP has remotely updated your firmware with a randomized, device-specific password. There is only one way to reset this: The Hardware Factory Reset.
Warning: This will disconnect your internet until you reconfigure the device. You will need your PPPoE username/password from your ISP (Call them first to get this). password zte f663nv3a exclusive
How to reset the ZTE F663NV3a:
After the reset: The exclusive ISP password is erased. The router reverts to ZTE factory credentials. Once you get the exclusive password, you might
Action Step: Immediately log in and disable TR-069 (Remote Management) to prevent your ISP from locking the device again remotely.
Telnet/SSH root access (if enabled):
root / Zte521 or root / root After the reset: The exclusive ISP password is erased
Even if the web portal is locked, the Telnet port (23) is often left open.
Once inside Telnet, you are the superuser. You can type sendcmd 1 DB p DevAuthInfo to dump all usernames and plain-text passwords stored on the device. This command is the holy grail of "exclusive" access.