Thanks for your help! I finally figured it out! I uninstalled my software firewall (though it was definitely deactivated) and my virus scanner (also definitely deactivated). What can I say? One of them must have blocked something in between the two jboss instances. Now everything works perfectly. I can easyly see that the nodes are switched via round robin. Can you imagine the cause? This took me hours, and I am not smarter than before... Regards, Oliver View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4127055#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...