sftp issue

Hi , I am facing an issue in connecting to sftp2.em2.cloud.oracle.com . When I initiate a connection through winscp it gives an error and when i close the session and reconnects it works fine .

The connection error mentioned below

Using username "xyz".

========================= Security Notice =========================

= This system is restricted to Oracle authorized users. =

= Unauthorized access may result in disciplinary action and/or =

= civil or criminal penalties. To the extent permitted by law, =

= use of this system may be monitored in accordance with the =

= terms of Oracle's Acceptable Use Policy. =

========================= Security Notice =========================

Authentication failed.