Samsung has released a new firmware update Software update T825XXU1AQD6 for Galaxy Tab S3 is now available. The update comes with April security patch update. However, only the LTE variant of the Tab S3 is receiving the update.
The update also includes regular bug fixes and system improvements.As the update is being rolled out over the air, it may take a while to reach your Galaxy Tab S3 device.
You can also manually check for the OTA update, just head over to Settings > About device > System updates. But before hitting the download button, ensure that your handset is sufficiently charged and connected to a WiFi network.