Third-party tools (e.g., ONT repair tool, HWFW_GUI) can:

⚠️ Warning: Modifying firmware may brick device and voids warranty.

Verdict: For 99% of users, stick with your ISP’s latest stable release. Only use custom firmware if you need advanced routing (e.g., converting the ONT to a pure bridge mode with Wi-Fi off).

The safest source. Many ISPs (e.g., Telmex, Claro, Vodafone, China Telecom) have hidden firmware pages for CPE devices. Search for "HG8245W5-6T firmware update [Your ISP Name]".