Penguin. This is going to be tough. 3 routers, that's really not a good network solution. I am guessing, it is setup that way to get further and further from the ISP source(modem). However, each time a new router is introduced, you are adding new DHCP and new NAT. you can't foward from one NAT/DHCP range to another, they don't see each other. In the instance above, you can't port forward any traffic from 192.168.0.1 to 192.168.1.120 , as the 1.120 isn't in teh DHCP range. The best you could try to do, would be to port forward all traffice on that port to 192.168.1.1 (but, you will need to know the private ip of that router, which should be something in the range of 192.168.0.2 through 192.168.0.254. You would need to do this same thing on the original router/modem 10.113.0.1 . forward all traffice on the port to the private ip of the router (192.168.0.1, which will have a private IP address in the range of 10.113.0.2 though 10.113.0.254) so, start on the modem/router from your isp..i am assuming that is the 10.113.0.1 router. Find out what the private IP address of your second router is (192.168.0.1 is the internal IP, not the private IP on the 10.113.0.xxx DHCP. follow the same steps on the next DHCP range. Then, your current port fwd on the 192.168.1.1 modem to 192.168.1.120 should work. However, with that being said, you honestly should try to remove the DHCP/NAT from the second 2, and utilize the DHCP from the original only. Set the next two to both be used as switches(most of the time, called Bridge mode). Doing this,will change the IP on your server, to something like 10.113.0.120 so you will need to setup port fwd in the first router to whatever IP your server gets.
the 10.113.0.1 may be a node router for the ISP. it is providing the dynamic addressing to your modem.
It is not uncommon for some ISP's not to hand out public IP's but private ones. The reasoning behind that is both control (so that you can't host things on your own) as well as protection (to a certain degree anyway) because "bad guys" have somewhat of a harder time reaching you (not always true though). But yeah: if your ISP set you up with the 10* IP address then this setup is probably not going to work unfortunately.
