Disclaimer: Modifying router firmware may void your warranty and violate your ISP's terms of service. Proceed at your own risk. Always keep a recovery plan.
However, like any complex networking hardware, the F670L can suffer from bugs, security vulnerabilities, or performance degradation over time. The common solution is a firmware update. Yet, if you search for a you will encounter a labyrinth of dead forum threads, malware-ridden download sites, and confusing version codes. zte zxhn f670l epon firmware link
A legitimate firmware link for an older EPON build might look like: https://zte-firmware.s3.amazonaws.com/ZXHN_F670L_EPON_V1.0.0P3N1_20220115.bin Disclaimer: Modifying router firmware may void your warranty