cannot connect to database using sql developer

Summary

cannot connect to database using sql developer

Content

I create an one node database in BMC and can successfully use sqlplus to connect to this db using the instructions https://docs.us-phoenix-1.oraclecloud.com/Content/Database/Tasks/connectingDB.htm .

However, I cannot connect to it using sql developer.

I created a ssh tunnel and it can connect to the instance:

ssh -L 9999:localhost:1521 opc@{database_public_ip}

I got "channel 3: open failed: connect failed: Connection refused" when connecting from sql developer using:

username: sysdba (also tried "sys")

password: my password set when creating this db

hostname: localhost

port:9999

service name: {ORACLE_UNIQUE_NAME}.{DOMAIN NAME}