How to get the latest firmware for TZ series SonicWall
A valid support contract for SonicWall is required for you to access the downloads page.
Navigate to http://www.mysonicwall.com and create an account with your devices serial #.
Go the tab marked Downloads and click on Download Center. After that select your TZ series SonicWall from the Software Type list.
Click the button for Add To My Downloads for the respective firmware version you've selected.
Save the file to your computer and login to the SonicWall unit you'd like to update.
Once logged in, navigate to System and then Settings.
Click Upload New Firmware and select your recently downloaded from the list. Then click Upload.
Now you're done. Allow the device about 10 minutes to properly unpack and install the firmware. You should know it's done when the devices lights resume normal operation.