Scenario: Untangle is at the edge of the network with a public static IP address on the external interface. If you have a dynamic IP address from your ISP, you will need to set up the dyndns or other means.
Remote client users have XP PCs.
Solution: Just follow the OpenVPN wizard and finish configuring the OpenVPN. Create the VPN user and issue out the OpenVPN client. Everything should work.
If you want to access resources via their name instead of IP address, you will need to go into the OpenVPN, Advanced, and export the DNS, and DNS Overrride, input the DNS server's IP address. You will need to use the fqdn when trying to access via their name.
Extra info: If the remote clients use Vista or Windows 7, you will need to install the OpenVPN as an administrator and run it as an administrator.
Mac users, you can use tunnelblick.