i21 Firmware V188.8.131.52(1418)_EN
1. enable the Airtime Scheduling.
2. Improve 1dB in PA for 5G signal.
3.Incorrect upgrade will damage your device.
4.Please upgrade your device by cable connections.
5.Do not power off the device when upgrading.
6.Please unzip the file you downloaded and use the file ended with "bin" or "trx" to upgrade your device.