Is it possible there is a bit of technobable confusion here?
Lets call it LAN side and WAN side. The LAN is your house, the WAN is the internet.
From my work PC, I just hit my house SME 5.12 via WAN side IP address using IE 5.5. If you want to hit it just for giggles,
http://195.174.194.112/ (DHCP and subject to change at the drop of a hat). Please don't expect much. This is one of my many half ignored projects..... The gallery is nice though! The slow speed is due to Turkey's cable modem service being pretty poor.....
As far as I understand this thing (that is not much...) it is 'impossible' to hit the LAN side IP address from the WAN side. That is the firewall and NAT at work. You are most likely using the test subnet (192.168.xxx.yyy) for the LAN side and would not want/use that on the WAN side anyway...
I believe some ISPs block port 80 requests. If you read the fine print of your agreement, there may be some bable about not running a web server.
Instead of using the IP address, why not use one of the fine and free dynamic DNS services?
Bill