That's not an authentication issue - the error message is telling you it can't reach the database server.
Can you ping the ip/server from your SQL Developer machine?
I am using user name as - sys and password as - oracle and also tried user name - hr, password - oracle I am unable to login. Please help
Error I get - Status failure test failed: IO ERROR:The network adapter could not establish connection.
I tried even my registered name to loin to oracle website even that does not work.
What are the OTHER connection parameters you are using?
Connection type - BASIC?
SID or Service Name?
All of those need to be correct.