I've got an R710 with an idrac 6 express. The system is running esxi 5.1, BIOS 6.3.0, Lifecycle Controller 126.96.36.199, and idrac6 1.95.05. On the network side it's using shared LOM1, which is shared with the primary vmware management interface.
The problem is that the idrac goes unresponsive after some amount of uptime. A reboot usually fixes it for somewhere between a few minutes to a few hours. The rest of the network (esx) is fine.
I have an identical system (same hardware, firmwares) works fine.
Could this be hardware related? Unfortunately my support just ended so I can't get hardware replacements. Anything else to try?