I have an R640 with an iDRAC9.  It has a problem in which the IP always responds, but SNMP/HTTPS are basically flapping - not available for hours, then available for a few minutes, up to 20-30 minutes.  

I upgraded the BIOS to the latest (2.24) and the iDRAC firmware (7.00.00.181) and it actually made the problem worse.  When I was able to finally get back into it, I cold reset the iDRAC.  It came back up and was accessible for about an hour, then stopped allowing HTTPS again.  I can SSH to it and get prompted for the RACADM login, but cannot authenticate while it's in this state.

Here is a picture of its avialability in our NMS.  The wider one on the right is right after I cold-restarted it.

Anyone run into this before and know of a solution to it?

TIA