I tried to write the first occurance off as a fluke, but I just started over on the same equipment, recreating a lab environment...
it occured again. When I try to enable passthrough on an lsi 9271-8i, then then reboot the host...I completely lose the management network. I tried resetting the ip address, reloading the services, nothing works.
I was in a hurry the first time, and simply re-installed esxi, and was able to get passthrough working after the fresh install. This time, I actually took out the raid card after the hang, and rebooted. The management came back to life.
I'll keep posting on what else I try, and what fixes this.
installed from iso:
VMware-VMvisor-Installer-5.1.0.update01-1065491.x86_64