For the F600W, there are almost no legitimate public firmware repositories. ZTE does not provide direct consumer downloads.
Method B — Web UI manual update (common) Zte F600w Firmware Update
Is your ZTE F600W router acting up? Learn how to perform a safe ZTE F600W firmware update to fix connectivity issues, patch vulnerabilities, and unlock new features. Step-by-step guide + troubleshooting included. For the F600W, there are almost no legitimate
Never update the bootloader unless necessary. And if your router works perfectly, but the firmware is stable and patched for known CVEs, you can skip the update. But if you see any instability, go for it. For the F600W