Before bypassing security, you must understand it. The F670L runs a custom Linux kernel (typically 2.6.x or 3.x) on a dual-core MIPS or ARM chipset (often a ZTE ZX279128S). The lock exists at three levels:
The primary lock mechanism is the TR-069 protocol (CWMP). Your ISP can push configuration files, change your admin password remotely, and close any backdoors you open within 24 hours. unlock zte f670l better
Before hacking firmware, try the enhanced super admin method. This works on 80% of F670L units manufactured before 2023. Before bypassing security, you must understand it
The ZTE F670L has a terrible NAT table. If you have more than 15 devices, the router will lag. The better unlock is turning the ZTE into a dumb ONT (optical transceiver) and using a real router (Asus, MikroTik, pfSense). The primary lock mechanism is the TR-069 protocol (CWMP)
If you are looking to simply remove the admin password restriction to access hidden menus:
ZTE Config Decoder: