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Xiaomi Up The Power
Are You Low On TX Power?
Some of the Mediatek 7628 based Xiaomi models does not use the all the available transmit power when running OpenWrt
Both the 4A 100M Edition and 4C I purchased in South Africa had this issue.
Fortunately the fix is fairly simple.
Up The TX Power - The Action Plan
The Flash chip of the device is segmented in various blocks.
One of these blocks is called factory and contains things specific to the device e.g. its MAC Address.
When the operating system then boots up it reads a know location on this bloc to get and configure the device with the correct MAC Address.
This block is also consulted when applying a limit on the broadcast power of the radio.
With the default values in the factory block some devices has a limit of only 14.0 dBm TX power on the 2.4 radio.
This is despite the fact that the radio on the device is capable to transmit much more.
To overcome this limitation we will do the following on each device:
Flash a copy of the OpenWrt with MESHdesk firmware in device (it has kmod-mtd-rw included already).
Make a backup of the factory mtd block.
Modify some values in the copy of the factory mtd block.
Write the updated factory mtd block back to the device.
Reboot
Enjoy more power.