There is an update rolling out to AT&T Galaxy S5 and Galaxy S5 Active devices, both based on Android 5.1.1 and contain some ‘device security improvements‘ or bug fixes and all that.
The build no. of the update is G870AUCU2CPB2 for S5 Active at AT&T, while that for regular Galaxy S5 is G900AUCU4CPA2.
The update is pretty minor, and ignore-able, but if you to keep your old device up to date, then sure hit the update button under settings to get an OTA.
As regards AT&T Galaxy S5 though, we have the update available below too for download. The zip file below contains the full update, build G900AUCS4CPA2, and is flashable using Odin.
The download page below directs you to our Galaxy S5 firmware download page, when we have provided the download link to G900AUCS4CPA2 update firmware.
To update manually, and thus without waiting for the OTA, all you need to do is download the update from our firmware page first (linked below), and then follow the guide provided on the firmware page to install it. It’s easy even for first-timers, just be sure to install drivers first.
We don’t have the build G870AUCU2CPB2 for AT&T Galaxy S5 Active available for download yet, so sorry if you were looking for that.