[Sony Xperia 1 III] arjun_m4:
First of all Thanks to johndaniel, htcmage, gorEisberg and Forbesii for their amazing work.

Hello, fellow Xperia users like you I had wondered why Sony had to go with this stupid idea of blocking some regions from accessing 5G, if they had played their cards correctly this could have been a huge hit.

Anyway, let's enable 4G+ and 5G

Note: I have tested this on my Xperia 1 III XQ-BC52 with EU firmware, and I have noticed a battery drain using 5G.

Important Note: You don't lose Wide vine if you follow this correctly because I didn't lose mine. BTW I don't take any responsibilities

And yeah you have to do this after every OTA so this is going to be fun.

Prerequisites:

* Xperia 1 III

* Windows Laptop

* Firmware for your device

* USB Cable

Downloading Firmware​

Download XperiFirm from https://xperifirm.com/download/xperifirm-v4-6-0/ and Install

Open the XperiFirm and Download the firmware for your device ( check your model number and download the firmware)

Preparing the Device for Rooting ​

* Back up all the data from your device.

Make sure the device is supported for Bootloader unlock by opening the dialer and enter the code *#*#7378423#*#* and then press Service Info -> Configuration.

If the Bootloader unlock status is Yes, then you’re lucky and continue the rest of the guide.

Visit https://developer.sony.com/develop/open-devices/get-started/unlock-bootloader/ and Select your device and enter IMEI and get the code.

Enable Developer Options and then Enable OEM Unlocking and USB debugging on your device.

Download Platform tools for Windows using this link

https://dl.google.com/android/repository/platform-tools-latest-windows.zip

Open CMD and go to the Platform-tools directory and enter the below command:

adb reboot bootloader

Once it’s in bootloader mode or fastboot mode you will see blue light then type this command on CMD:

fastboot oem unlock 0xYOURKEY

Wait for the reply on cmd and then type

fastboot reboot

Now your device is Unlocked.

Rooting
​

Open the firmware folder you have downloaded and look for boot.sin file it looks something like boot_X-FLASH-ALL-4BA8.sin with around 96MB size (might look different for other versions and regions)

Download UnSin Exe from https://xdaforums.com/t/tool-unsin-sin-v3-v4-v5-unpacker-v1-13.3128106/ and then drag and drop the boot.sin this will give you boot.img

Rename the boot_X-FLASH-ALL-4BA8.img into boot.img (easier to flash) and then using Magisk Manager to patch it.

Just don’t delete the original boot.img we need that for the re-locking bootloader.

Now copy the magisk_patched.img into the Platform-tools folder and rename it into boot.img

Open CMD and go to the Platform-tools directory and enter the below command:

adb reboot bootloader

Once in fastboot mode type this command

fastboot flash boot boot.img

Wait for it and then type

fastboot reboot

Open magisk and verify it's rooted.

Enabling 5G​

Open CMD and go to the Platform-tools directory and enter the below command:

adb shell

su

setprop persist.usb.eng 1

If the phone, asks for Allow access press Deny.

After that, it should show up 3 Xperia on the device manager and install one by one manually using Qualcomm driver just youtube this part. Use Qualcomm USB diagnostic 9091 or 9081.

Download QPST from https://qpsttool.com/ and install and open EFS Explorer and select LAHAINA if the name is there otherwise try one by one until you see a bunch of folders.

Once all the folders are showing up go to Policyman folder and copy carrier_policy.xml attached in this post and paste it there.

Restart the device.

You should now have the Speed of 5G or 4G+

Don’t stop here.

Time to go back to Stock (Unroot) ​

Open CMD and go to the Platform-tools directory and enter the below command:

adb reboot bootloader

Remember the original boot.img we have before patching copy that file into platform tools and replace it with the patched magisk boot.img

Then type this command:

fastboot flash boot.img

Once that’s done then type this command:

fastboot oem lock

Wait for the response and then type this command:

fastboot reboot

Once that’s done your device should format and bootloader locked and back to stock ROM with 5G.

In case if anyone is facing any issue or have doubts comment down below or contact me on my WhatsApp +97333956356