While official firmware is restricted, the community has developed several "patched" or alternative builds for this hardware platform (Balong V700): OpenWRT/LEDE & DD-WRT
Look for version strings like 10.0.1.1(H187SP...) . Ensure the hardware revision matches yours exactly to avoid "bricking" the device. 2. The Write-up: How to Flash Patched Firmware huawei b311221 firmware download patched