This appears to be a home or a non-server (serverless) network. Assuming that to be true, set one router to be the master router. It needs only be a wired router. Log into the router and determine the DHCP range (it is probably something like 192.168.1.100 - 192.168.1.200).
Log into the wireless router, turn off DHCP on the wireless router. Plug a wire from a LAN (internal network) port on the wireless router to a LAN (internal network) port on the wired (main) router.
Set the IP addressing on the wireless router (where you set up external network) to a fixed address on the wired router (192.168.1.10 in the example above).
Now any connection (wired or wireless) should get the same range of IP addresses (192.168.1.101, 102, 103 etc.) Once you have confirmed this part, you can begin networking the computers.
... Thinkpads_User
