dear friends,

I have a strange behaviur when I try to connect to the database, maybe you can help me.

I have Oracle 11. When I try to connect from a client to the database DUC I am getting error ORA-12537 TNS connection refused.

On DUC I have the client's hostname introduced in sqlnet.ora file. After I reload the listener DUC the connection works. After a time the connection does not work anymore even if I did not made any changes to listener relevant files. A reload always fixes the error.
Can you please tell me what could be the reason for this and how can I solve this issue?

Kind regards,