iDRAC firmware 2.40.40 was released on 17th Oct 2016. Details can be found by following this link.
We have recently had the need to upgrade our iDRAC firmware to 2.40.40 on one of our servers while troubleshooting another issue with Dell and found shortly after that this particular server was no longer able to be discovered by Dell OpenManage Essentials.
We found that the TLS protocol the iDRAC set after updating was set to version 1.2, which is not supported by Windows operating systems less than Server 2012 R2 (Our OME server runs on Windows Server 2012). There is a patch available to fix this. This is all covered in the driver release notes.
The other alternative, which we have chosen to do for now as this firmware is only on one device is to set the iDRAC to use the older TLS protocol, which can be found under the iDRAC Network Settings in the services tab:
I’ll apply the Microsoft patch to the system, and then set the TLS back to v1.2