The chipset differs (Balong V7 vs V9). You will destroy the radio module.
And when someone asks her now about b311221, she smiles and says, “It’s a story about doors.” b311221 unlock firmware link
For features like band locking, you often don't need new firmware. You can use mobile apps like "HManager" or "Huawei Ctrl" that interact with the router's API to change bands without flashing. Conclusion The chipset differs (Balong V7 vs V9)