I am getting a very long delay (about 2 minutes) opening initial connections on my 11g2 development server. Sometimes I get
ORA-28547: connection to server failed, probable Oracle Net admin error and no connection at all.
However, the problem disappears on the second attempt.
The problem occurs with multiple clients: our app under development (using occi), SQLPlus, SQLDeveloper.
Edit: Additional information. Using strace, I see the client sqlplus establish a TCP connection on the correct port of our Oracle DB server. Some data is exchanged ok and then the client hangs on a socket read.
On a hung connection:
On a good connection: