I had same problem and I solved it by adding package address in all hosts files on all servers with let's say proper name and alias. Of course if you have NAT between internal and external network you had to add that package IP address on access list of allowed adresses. I hope this will solve your problem too (I don't know why but with resolving on HP-UX I have problem and I have to have in /etc/hosts all my IP's and names and aliases if I want that my servers know each other )
Best regards