When using Oracle.ManagedDataAccess v23.7.0 to connect to a host I am getting an error

ORA-50000: Connection request timed out

When using Oracle.ManagedDataAccess.Core v23.7.0 to connect to the same host, I am getting this error:

ORA-12545: Connect failed because target host or object does not exist

I am using a connection string shown here:

string connectionString = "Data Source = " +
"(DESCRIPTION=(CONNECT_TIMEOUT=15)(TRANSPORT_CONNECT_TIMEOUT=5)(RETRY_COUNT=3)(ADDRESS_LIST=(LOAD_BALANCE=ON)(ADDRESS=(PROTOCOL=TCP)(HOST=myhost.oraclepany.nl)(PORT=39000)))(CONNECT_DATA=(SERVICE_NAME=TestServiceName)))";

Any ideas why these errors occur?