two publishing problems

I have a bit of a weird problem. I managed to install Zulu and get it going. I managed to link it to iCal and an iPhone and all the calendars interacted dynamically. I am using it in demo mode and I inadvertently introduced more than the the limited 5 calendars. When i "published" this I naturally got an error messages saying there were too many calendars. So I reduced the number of calendars to 5 and then republished. From that moment on, my calendars in iCal and iPhone "appeared" to be OK, meaning that they could refreshed in iCal without bringing up error messages, but the data was no longer dynamic. Changes made in iCal did not appear in Filemaker and vice versa.
Now I have an added problem in that I have changed the computer Filemaker server is on and although I am pretty sure that I have not changed any of the configuration, when I publish I now get a local URL which looks like this http://10.0.1.55/zulu/calendars/SeedCodeCalendar/ whereas previously the URL had my dynamic DNS external IP address http://blahblah.com/zulu/calendars/SeedCodeCalendar/ which obviously it needs once I'm accessing it outside of my local network.
Any ideas for resolving these issues ?
Now I have an added problem in that I have changed the computer Filemaker server is on and although I am pretty sure that I have not changed any of the configuration, when I publish I now get a local URL which looks like this http://10.0.1.55/zulu/calendars/SeedCodeCalendar/ whereas previously the URL had my dynamic DNS external IP address http://blahblah.com/zulu/calendars/SeedCodeCalendar/ which obviously it needs once I'm accessing it outside of my local network.
Any ideas for resolving these issues ?