The phrase "Firmware upgrade impossible for HG8245H" is not a user error; it is a testament to Huawei’s enterprise security strategy. They designed the device to be a locked appliance for ISPs, not a hobbyist tinkering platform.

However, if you search the depths of network engineering forums, Reddit, or Huawei technical groups, you will find a recurring cry of frustration:

Some firmware versions (e.g., V300R013C10SPC118) have weaker signature checks.

This distinction is the root of the problem. The hardware is standardized, but the software is proprietary to the service provider.