Disable boot from DVD drive on DL180 Gen 9

Hi all,

  I have a requirement to disable booting from the DVD drive on a DL180 Gen 9 server.  The DVD drive is a SATA drive connected to the B140i controller.  In the UEFI BIOS (RBSU), I've attempted to remove the DVD drive from the boot order, but it returns after I reboot the server.  The best I can seem to do right now it to place it last in the boot order.  I've also found an area to control boot parameters for the embedded controller, but there are no settings to change.

  Any ideas?

Thank you!