Your response makes total sense to me and I do understand how it can be confusing... no problem.

First, it matters NOT that your internal domain and external domain are different... the CEICW will take care of that.  Also, you will always find a "MORE INFORMATION" button on every wizard screen.  This button provides invaluable help info that can guide you should you get lost.

Here's what you need to do when you RE-run the CEICW (you can run that thing as often as you like, it just keeps fixing whatever it needs to):

1.  Make sure your router/firewall has a LAN IP address in the same subnet as your server so, it should be something like 192.168.1.1.  If what you meant is that you have a FIREBOX SOHO router, then it doesn't have UPnP, so you need to manually configure the following ports to point to 192.168.1.20 internally:

25 - SMTP
443 - HTTPS (for RWW and OWA)
444 - SharePoint
1723 - PPTP VPN
3389 - RDP for remote administration
4125 - Remote Web Workplace

If you have some other kind of router that does have UPnP, it should be enabled during the setup and can be disabled after for security reasons.  Having UPnP allows the SBS to automatically configure those ports.

Your router, I'm assuming is already making your connection to your ISP and is probably providing DHCP (although it's much better if you have the SBS do it... but leave that alone for now).  So it doesn't matter that the CEICW only gives you the router option... that's what you have.

2.  Enter your ISP's DNS servers as requested and the LAN IP of your router (if as I suggested above is right, then 192.168.1.1). And tick the box that you only have one NIC so that you can be prompted to understand the rest of what I'm putting down in this post.  :-)

3.  On the web services screen, I suggest that you check all but the Business Web Site (port 80).

4.  Now, on the web server certificate you need to put your Public FQDN, OR your Public IP address if you don't have one registered.  I'd suggest that you use a registered domain name because that way users can remember how to access the server remotely (ie, http://server.domain.com/remote for Remote Web Workplace).  Wherever your DNS is hosted (usually your ISP or the registrar of your domain) is where your MX record is that points to your server.  You can just find out what that is by doing an nslookup on your PUBLIC (external) IP address not the internal one as you've stated above.  If it doesn't come back with anything, you don't have a PUBLIC FQDN so you'll have to use your IP address for now.

5.  On the next screens, you'll select USE Internet Email, USE DNS, and USE Exchange - delivered directly.

6.  On the Email Domain page, put in whatever is registered, ie, my-company.com.  Remember this does NOT matter that it's even close to what your internal domain is.  In my own system, I have a completely different domain name than my email domain.

7.  I'd suggest that you check the box to block attachments, and then click finish.  If you ever want to see the full settings of what you've done, just go to C:\Program Files\Microsoft Windows Small Business Server\Networking\ICW and you'll find a record of each time you've run the CEICW in both html and vbs formats.  (the vbs is in case you want to revert to those settings).

That should be all there is to it.

If you want to test your connection, go to http://dnsreport.com and use the box on the right to see how your email domain resolves.

Good Luck!

Jeff
TechSoEasy