Time out while connecting to the database. Current time out value is 30 seconds
Better use TNSNAMES.ORA file in your client. You can set Instant Client's timeout in SQLNET.ORA file

%ORACLE_HOME%\admin\network\

ORACLE_HOME is where your Instant Client binaries are and should be already added to your local environment variables.

If you don't know what Instant Client is, it is a binary dll that provides connection, execution and fetching capabilities over network. sqldeveloper has a lite one inside it's "installation" (read unzipped) folder, but you either have to reference to that manually, or install a proper one yourself. It can be downloaded from Oracle.com