The "Huawei ONT Firmware" threads on or ChinaDevices.com are the best community sources. Look for users with high post counts.

Firmware updates frequently resolve SIP registration failures and audio distortion on the POTS telephone port. 3. Where to Safely Download EchoLife HG8321R Firmware

Fixes for random reboots or "ping spikes" during heavy usage. Feature Compatibility:

Open a web browser and enter the default IP address: 192.168.100.1 (or 192.168.1.1 depending on ISP customization).

Here are the only safe sources to obtain the firmware: