Owners of many different variants of Samsung's Galaxy S6 flagship worldwide have gotten their hands on the update to Android 7.0 (Nougat), and now, owners of the Galaxy S6 Edge+ on AT&T are getting that update. The update in question comes with Nougat and everything that entails, including a whole new UI that somewhat resembles bits and pieces of Samsung's Good Lock experiment, the same UI that owners of the Galaxy S7 and its siblings, including the Galaxy S7 Active and the Galaxy S7 Edge, recently got. The update also brings Samsung Pass, Samsung Cloud, and a few under the hood tweaks and bug fixes, including network performance upgrades specific to AT&T. Last but not least, this update brings devices that take it up to the March security patch level. There has thus far been no word from AT&T on when the April patch may arrive.
The update will bring your device's build number up to NRD90M.G928AUCU4EQC6, but if you're coming fresh from going back to stock after a custom ROM or haven't updated in a while, keep in mind that you'll need to be on version number G928AUCS4CQA1 or G928AUCS4CQB2 in order to get this update. The kernel version is brought up to 3.10.61-10809541, while the baseband version is now up to G928AUCU4EQC6. The new baseband version means a new radio, which means that users may notice somewhat different network performance; whether that's worse, better, or you notice no difference will all depend on your location and the number of AT&T towers and users around you.
According to AT&T's website, the size of the update can run "up to 1.51 GB", which likely means that how much downloading you'll have to do will depend on what software version you're currently on, though there may be other factors involved. In any case, it's a good idea, as with any update, to make sure the phone is on a charger, or at least up to 80% charge or higher on a reliable battery before taking the update. It should be live for all users, so if you're not seeing it a reboot may be in order. AT&T has not announced whether the update will hit unlocked units being used on other networks, so if this is your scenario and you're not seeing the update, heading to an AT&T store may be the only way to get the update, outside of flashing it manually with Kies, Fastboot, or ODIN.