Extract Huawei E303i-1 Firmware 21.521.17.00.00 on your computer
Install the Firmware update file for Huawei E303i-1 downloaded from Huaweiflashfiles.com
Follow the procedure for updating Firmware that is given in Package.

Huawei Flash File | Size: 15.34 Mo
Version: 21.521.17.00.00
Operator: Universal
Operating systems: Windows 7/8/10/XP/Vista
Huawei E303i-1 Firmware Download