What you want is not possible. This is not how TCP/IP works.

By using a router, you create a new network, so obviously, things as file sharing stop working, as they only work with your internal network.

You should place the webserver either on your own computer or place the machine with a secondary IP in the network where you optionally use DNS to make people find that server (for example through the hostname, or by asking nicely to get a DNS entry through the DNS server.

Also, it is really a bad idea to put so much emotion in your post. I almost not made this answer and was like: screw him.

What you want is not possible. This is not how TCP/IP works.

By using a router, you create a new network, so obviously, things as file sharing stop working, as they only work with your internal network.

You should place the webserver either on your own computer or place the machine with a secondary IP in the network where you optionally use DNS to make people find that server (for example through the hostname, or by asking nicely to get a DNS entry through the DNS server.

By using a router, you create a new network, your traffic remains inside this network and by port forwarding on the router, you can selectively allow traffic to go from the outside of the network to the inside. If this were not the case, I could access the files on your computer through the internet. Its just not possible. Again, TCP/IP does not work that way.