Samsung has started pushing an April security patch to three particular devices namely Galaxy On7 2016, Samsung Tab A 9.7, and S4 Value Edition. The update is on-the-air as we speak. So you should receive it soon if you have not received it yet.
The update will appear on the Galaxy On7 2016 devices with a build number G6100ZCU1AQD2, while the Samsung Tab A 9.7 will get a build number I9515XXU1BQD2 and the S4 Value Edition update will have a build number P555CZCU1BQC1.
The update carries with it regular security patch as well as bug fixes and minor tweaks and improvements. Among the three devices, the S4 Value Edition is the oldest while the Tab A and Galaxy On7 are devices launched last year. We do not expect the S4 to get the Nougat update but it is good to see Samsung take some time to push security patches to the S4 which is a very old device. Given Samsung’s track record even the other two devices have a very slight chance of receiving Nougat update.
Samsung has already rolled security patches for Samsung Galaxy J7 (2016) and Galaxy S7 and Galaxy S7 Edge in India and other regions.
If you want to check the update manually go to Settings > About device > System Updates. Make sure the device is at least 50% charged and connected to WiFi before installing the security patch.