as far as I understood you tried to access your webserver in lan by the same ip as you do from wan. If though what does traceroute say?
How is your port fowarding configured?
Regarding to your traceroute I suppose your port fowarding configuration is incomplete.
Your router knows its ip-adresses (including the one you wanted to access), so you are directly sending your query to your router (which I assume is also your default gateway).
Problem here is the most common operating system on routers assume you only want to foward ports from your "internet interface" (most common pppoe) to your lan bridge. As result of that there will be no option in the web interface to configure port fowarding from the lan bridge. Without Portfowarding in your lan interface your router will drop all packets directed to this ip.
Maybe you can configure your router via cli, e.g. ssh or telnet.
What router are you using?
There are some options now to fix this:
1.) Use the local Ip-Adress to access your webserver
2.) Try to solve the problem descriped in my frist Edit.
3.) Get a router/os that supports local portfowarding(destination nat)
If you got enough time i would suggest 2.) followed by these steps:
1. Enable ssh or telnet in your router
2. Download putty or activate telnet in windows (i assume you are using a windows machine)
3. Connect via ssh or telnet to your router.
4. Search the cli manual of your router for a option to setup portfoward(maybe called destination nat)
Found this right here in forum Thread i think this is the same problem you got. Maybe the solution to unix based router operating system there does work for your router.