>all of the oracle services start except the OracleOraHome81ManagementServer.

I think you need to get the Oracle Management Server (service) started.
oemctrl oms start


FYI:
VTK-1000: Unable to connect to the Oracle Management Server. Please verify that you have entered the correct host name and the status of the Oracle Management Server.

Cause: The connection to the Oracle Management Server described above failed.

Action: Verify that you have entered the correct host name, and verify the status of the Oracle Management Server.

HTH