Check that everything works fine. Make sure you create a backup from the System Settings page before proceeding with the upgrade. In case something goes wrong, you can restore the backup.
Go to the System Settings again, click the “Check for Updates” button to upgrade to the latest version.
You might lose your configuration in the last step. If that happens, you can either configure everything from scratch, or restore from your previous backup. However, restore Access Control only. Restoring whole backup from an old version may cause WiFi to malfunction.