For epo 4, I had the same problem on my win2008 server. I had to add the IP address ranges to the local intranet sites in IE security. See microsoft kb 303650 "intranet site is identified as an internet site when you use an fqdn or an ip address"
I have been part of a team "Consolidating" 13 state agencies. My part is AV. Each Agency had their own way of doing things and we did not have centralized WINS(For older WinTel boxes) or DNS. So name resolution is a huge issue. Further, each agency had their own firewalls so I had issues there as well.
My main EPO server is now a subnet with the proper ports open on a firewall. For name resolution, I added the each agencies Wins/DNS server to my IP Settings then HOPED I didn't bump into a firewall on their end.
Some agencies still run some really old Novell Netware stuff and that adds another layer of challenges.