that you had a big network and people out on the road, accessing it remotely via a router. Someone sends a request to your server for a file, and the server duly sends the file out. The router uses IP routing to determine the path that the data will follow to get to its destination - it builds what's called a forwarding table, so it can work out the next hop to get the data to its destination.
That's an extremely simplified explanation of a complex process, and there are various IP routing protocols. You may want to turn IP routing on again, it doesn't represent a security threat.