cannot set java.rmi.server.hostname on children of rmid in time

It is not possible to set the java.rmi.server.hostname property on children of rmid in time for it to take effect. If you pass it as one of the properties in the activation group descriptor, the activation group impl's constructor will call its superclass constructor before setting any properties, and the superclass constructor will export the group impl as a remote object, causing the static initializer in sun.rmi.transport.tcp.TCPEndpoint to get run, which reads the hostname property (before the group gets a chance to set it).