Thanks Bernard. The problem is solved!
I switched to use the JT400.JAR that comes with Client Access (as you are using) and the lost connection problem has gone.
In the default installation of Client Access, or iSeries Access, the driver is here:
C:\Program Files\IBM\Client Access\jt400\lib\jt400.jar
I had the lost connection problem using the latest open source version from JTOPEN_6_5_1, so it looks like something changed in the driver.
From: Harris, Bernard
Sent: Tuesday, August 18, 2009 4:58 PM
To: Lennon , Sam
Subject: RE: [Squirrel-sql-users] Constantly losing connection toAS/400(iSeries) Host
Here is the Metadata for our production machine:
JDBC Driver CLASSNAME com.ibm.as400.access.AS400JDBCDriver
JDBC Driver CLASSPATH C:\Program Files\IBM\Client Access\jt400\lib\jt400.jar
getDriverName AS/400 Toolbox for Java JDBC Driver
getDatabaseProductName DB2 UDB for AS/400
getDatabaseProductVersion 05.04.0000 V5R4m0