We’ve already see quite a few Android 5.1.1 updates rolling out today, but it seems there is more: The T-Mobile LG Leon is also seeing an upgrade to Android 5.1.1, that the carrier says is a mandatory update.
Software version of the LG Leon 5.1.1 update is H34510f.
Apart from updating the LG Leon to 5.1.1, version H34510f also patches the Stagefright vulnerability on the device.
If you haven’t received the H34510f update on your LG Leon yet, then you better check for it under Settings > About device > Software info. Look for system update now.