Hrm. I'm actually not sure where you would set specify the IP for the WPE (I'm new to FileMaker Server). When you bring up /config/fmi in the https web page, it claims that the Web Server is on 128.2.10.142 (I haven't found where you can change this). And it says that the Publishing Engine isn't responding on localhost even though it is definitely installed on the same machine. I've even tried to change this to the hostname, but the server won't let me commit any changes (the button is grey'd out).
If screenshots would help, I can send those over. Any of the configuration that's been done has been without using SSL (such as IP restrictions to the Admin console). As soon as I turn on SSL, load up the admin console on https, log in (successfully), it has "An unexpected error has occurred" in red at the top of the Overview screen.
I'm sorry if i'm not quite following you :)