AT&T is planning to rollout the Android 5.1.1 update for Galaxy Note 4 and Note Edge devices from tomo, October 10, but it looks the update has already started hitting some devices a day earlier.
Or, at least for the AT&T Galaxy Note Edge, whose one user received an update notification today, and says the update is sized 697.51 MB. The update is huge one for both sets of users, because it’s finally, finally Android 5.1.1 that’s rolling out.
If you own a Note 4 or Note Edge at AT&T, then be sure to check for an update under Settings > About device. You should get a notification for update to build N910AUCU2DOI2 and N915AUCU2COI2 respectively for AT&T Galaxy Note 4 and Note Edge respectively.
Know that you will lose root access upon installing the update, if you have it already, and that right now, no root solution is available for AT&T Note 4 and Note Edge for 5.1.1.
There is nothing else mentioned as part of the Changelog for Oi2 update, but the mention of 5.1.1 is enough for you, right?