Extend NHibernate DriverConnectionProvider class

I am working on an old web application. It extended DriverConnectionProvider

NHibernate to establish a db connection. Below is the code.

public class NewConnectionProvider : DriverConnectionProvider
{
   public override System.Data.IDbConnection GetConnection()
   {
        IDbConnection conn = base.GetConnection();       
        //execute a SP here.. to set up proxy user to connect to
        //oracle db
       return conn;
   }

}

 //connection string
<add name="connname" connectionString="Data Source=(DESCRIPTION =(ADDRESS_LIST = (ADDRESS = 
(PROTOCOL = TCP)(HOST = .....)(PORT = ....)))(CONNECT_DATA = (SERVER = DEDICATED)
(SERVICE_NAME = ....)));Min Pool Size=5;Max Pool Size=500;Proxy User Id=....; 
 Proxy Password=.....;Validate Connection=True;Connection Timeout=100;" />

      

        
        
        
      

    

Question: The problem we are facing is that the number of connections is related to the Max Pool Size

connection string. Sometimes we get a connection timeout error. How does joining join work in this case? Do I need to override as well DriverConnectionProvider.CloseConnection

? If so, when do I need to call? The system uses NHibernate, Oracle 11g.