[CentOS] systemctl reboot -- server not accessible after reboot

Hi,

Such a simple problem, but I can't figure out the cause.
Supermicro server with a Xeon E3-1200 cpu.
1U entry level item.

Using CentOS 7

from ~$root --- systemctl reboot

Server disconnects my ssh connection and never comes back up.
Go to the server and the power is on but the server is not accessible by ssh.
When I connect a monitor and keyboard --- non-responsive.  It's like
it's in suspend mode.

I push and hold the power button until the server fully powers down.
Push power again and everything boots, goes to prompt, and all is well.

When I try systemctl reboot directly on the server.
Same problem --- does not start to login prompt.

Manually power down and power up again --- works and all is well.

Anyone have this problem before?
I've checked all the BIOS options and I can't find anything misconfigured.

Thanks for your help.

Mike