On some machine, the network IPv4/IPv6 dual-stack is available.
It may be enabled, even if the network is configured to be an IPv4 network.

Besides, by default, the JVM uses IPv6 if it is available.
In this case, for performances reasons, the Petals ESB startup script forces the usage of the IPv4 stack.

If your network is a full IPv6 network, you must update the Petals ESB startup script and remove the option -Djava.net.preferIPv4Stack=true or replace it by -Djava.net.preferIPv6Stack=true.

More information on network properties of the JVM can be found on Oracle's web site.