Stock Android 6.0 Marshmallow for T-Mobile LG G4 H811 is now available, some users have updated their devices to H81120i firmware and also shared screenshots. Previously it was released for unlocked LG G4 in Europe and Canada. The H81120i Stock Marshmallow firmware for T-Mobile LG G4 H811 is based on Android 6.0 Marshmallow and brought all new interface with multiple improvements and improved security patches. The H81120i firmware for T-Mobile LG G4 H811 is not rolling out via OTA instead you need to connect your device to PC via LG Bridge.
LG Flashtool Method (Manual process): To manually update T-Mobile LG G4 H811 via LG Flashtool requires Marshmallow firmware KDZ files [will be available soon] but as it becomes available via OTA you will be notified further you can check the updates by following the below mentioned procedure.
Update H81120i Stock Android 6.0 Marshmallow on T-Mobile LG G4 H811 via OTA
To update T-Mobile LG G4 H811 on Android 6.0 Marshmallow firmware you don’t need to download multiple file for it, just you need your device and the working internet connection. You must also remember that OTA process works only on Stock devices which means your device is no longer rooted while you searching for latest firmware via OTA. If you think your device is rooted then don’t waste your time switch to alternative firmware update processes or if possible un-root it and then give it a try. But we don’t recommend you to get stuck in such a long un-rooting process just manually if the download link is available. If you think you are all set to go, then
Go to device Settings >> tap on About device >> Software updates.
Now tap it to check the latest available firmware. Upon it’s availability you will be prompted about the update, now what just tap “Download Now” to instantly download the firmware or “Download later” if you wish to download later. Some times it depends on the region too for example, if the update is released for a specific region but you are not present there it will take some delay until firmware update reaches that region.