Extract Huawei E3531s-1 Firmware 21.318.29.00.1137 on your computer
Install the Firmware update file for Huawei E3531s-1 downloaded from Huaweiflashfiles.com
Follow the procedure for updating Firmware that is given in Package.

Huawei Flash File | Size: 14.37 MB
Version: 21.318.29.00.1137
Operator:Airtel Uganda
Operating systems: Windows 7/8/10/XP/Vista
Huawei E3531s-1 Firmware Download