Making two networks visible to each other
I have made a rough drawing of my network layout: 
The gateway, the two servers and the wifi router have a global IP address with a subnet mask of 255.255.255.240.
The PCs have local IP addresses in the 10.0.1.x range and a subnet of 255.255.255.0
What I need to do:
Make the two servers accessible from the PC's local network and vice versa. The servers are running Ubuntu and the PCs are Windows, Ubuntu and Macs. Can this be accomplished by adding a route in the Ubuntu servers, or assigning them two IP addresses? I don't really know how to go about it.
Any help would be appreciated. Thanks!
Edit: More Info:
- I don't have access to the gateway. It's provided by the ISP
- The servers (and the gateway) have global IP addresses. That's why I can't combine them into a single network.
- The router is an Apple Airport. I'm not sure of the model. But I don't think it can do much.
I understand that there is no definite solution to this with my current hardware and network topology. As some of you have pointed out, I can easily access the Servers from the PCs with LAN-speeds. I can live with that for now.
could you please post a traceroute from the pcs to one of the servers using its IP adress. (i think this should work fine, but not if you use the servers names as name resolution broadcasts do not cross subnet boundaries, which can be fixed by adding the servers ips and names to the hosts file)
the reverse could be tricky as the router is running nat. what ports do the servers need to acccess on the pcs?
Actually this is quite a bit of routing in the question.
Problem with your setup.
- Your typical wifi router usually would not support routes manually entered. If you want you can see if the firmware is replacable by e.g. openwrt, dd-wrt solutions, which are linux-based and can allow such modification.
- You can consider setting up static routes & iptables rules that allows external network to go into the internal network. but remember, you have to setup the gateway so that the static routes points back to the wifi router that is properly configured.
- setup a static route for 10.0.1.0/24 to the wifi router on the gateway
- setup the e.g. iptables on the router so that it allow the two subnets be connected