iDRAC service module error ISM0006

I'm having trouble getting the iDRAC service module set up on a 7920 rack.  It's running CentOS 7.6.  The service module installer shows iSM is unable to communicate with iDRAC. Please refer the FAQs section in Install Guide.

In the web GUI, it shows that the module is installed but the connection status is Not running (TLS error)

syslog shows: 

ISM0006 [iSM@674.10892.2 EventID="8193" EventCategory="Audit" EventSeverity="error" IsPastEvent="false" language="en-US"] The iDRAC Service Module is unable to communicate with iDRAC using the OS to iDRAC Pass-through channel.

I looked at the instructions here, but it seems to be already set correctly.  I have another machine set the same way and it works.

# racadm get idrac.os-bmc
[Key=idrac.Embedded.1#OS-BMC.1]
AdminState=Enabled
OsIpAddress=0.0.0.0
#PTCapability=Capable
PTMode=usb-p2p
UsbNicIpAddress=169.254.0.1
#UsbNicIpV6Address=fe80::1234