There’s no denying the fact that AT&T is the laziest of all carriers in the US when it comes to rolling out Android updates. And the AT&T Galaxy S7 and S7 edge Android Nougat update will suffer from that.
Google has announced the release of Android Nougat update by the end of Summer 2016. Which means Samsung will most probably get the Android Nougat update to the international variants of S7 and S7 Edge by the end of November 2016.
But for the AT&T S7 and S7 Edge, Android Nougat update will be delayed further. Generally it takes more than 3 months for AT&T to release Android updates after a manufacturer releases the update to its international variants of the device.
If we expect Samsung to release Android Nougat update for international Galaxy S7 and S7 edge by the end of November 2016, then the AT&T s7 and S7 Edge Nougat update should arrive by February or March 2017.
Expected AT&T S7 and S7 Edge Nougat update: February or March 2017.