Are you using an OCI/Thick or Thin JDBC driver connection? If Thin, then perhaps you are being impacted by the following:
SQLDeveloper Receives "java.sql.SQLRecoverableException: IO Error: Connection reset" And ORA-609 In Database Alert (Doc ID 1483287.1)
So if you are getting an ORA_609 in the database server's alert log and its sqlnet.ora enables the following security banner settings
SEC_USER_AUDIT_ACTION_BANNER = ...
SEC_USER_UNAUTHORIZED_ACCESS_BANNER = ...
this may be the problem, which comes from a bug with the title "JDBC THIN DOES NOT CONNECT WHEN SECURITY BANNER IS SET IN DATBASE "
Hope this helps,
SQL Developer Team
Thanks for your feedback. We actually found what was wrong. The connection used "Port Forwarding" to create a Secure Shell connection and a patch to the Oracle database server reset the configuration "AllowTCPForwarding" to NO. When we discovered this and set it back to YES it worked again fine.
Thanks to all who viewed and input.
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