Disable Auto Firmware Update - SXR50/SXS50

I have the SXR50 and 3 SXS50 satellites.  The recent firmware update (V4.3.2.200) totally dorked up the routers.  I would experience disconnects to wireless and hardwired devices were not picking up IPs correctly.  

I reverted back to the previous firmware version (V4.3.2.100) and all issues were resolved.  However, the option to disable Auto Update for the firmware is greyed out.  Any idea why this would be and how to allow me to disable it so I do not run in to this again?