AT&T is currently pushing out an update for the Samsung Galaxy S5, which bumps the device from version OC4 to OF2. Unfortunately, AT&T has not provided a list of changes that are made in this update, but we do know that it is still based on Android 5.0. The download, which is around 297MB in size, can be downloaded now and installed on your device.
If you are not seeing the notification for the update, you can head into Settings and About Phone and check manually for the update. Have you already received the update? If you have, and noticed any changes, fixes, or issues, be sure to let us know in the forums.