I've verified I can connect to a local Oracle database (via Oracle's SQLDeveloper). My tsnnames.ora is
tnsnames.ora Network Configuration File: C:\app\RonM\product\18.0.0\dbhomeXE\NETWORK\ADMIN\tnsnames.ora
Generated by Oracle configuration tools.
XE =
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = Dell20190320.home)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = XE)
)
)
LISTENER_XE =
(ADDRESS = (PROTOCOL = TCP)(HOST = Dell20190320.home)(PORT = 1521))
ORACLR_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
)
(CONNECT_DATA =
(SID = CLRExtProc)
(PRESENTATION = RO)
)
)
and my Oracle Connection Manager shows

Not sure what I'm missing?
Thanks