As the AT-OMNI-238 is Dante IP-to-Analog Bridge hardware, the method for updating the firmware on this unit is via Dante software.
Dante has moved the Firmware Update option for its products to its Dante Controller software. The current way to update Firmware is through the "View", Dante Updater highlighted below:
To update an OMNI-238 you must first download the firmware from the product page. Once the file is downloaded, extract the Zip folder. Notate the location of the AT-OMNI-238 18.104.22.168.dnt file.
In Dante Updater click Library
Find Imported Files
Click Import Firmware at the bottom of the window
Select the AT-OMNI-238 22.214.171.124.dnt file that you extracted in an earlier step
Click on Home in the Red Menu Bar
Select Imported Firmware Files
The OMNI-238 must be online and connected to the network for the next step:
Select the OMNI-238 from the list and under action select Load or Reload
On the next screen verify select the checkbox acknowledging that audio will be interrupted during this process and select Update Now.
Update Status Progress Bar will show progress of the firmware process
You will be returned to Dante Controller when the update is complete.