It's possible that the server has a static address, on the private network 192.168..., with the clients on DHCP and the new router is assigning a private network of 10.1...
This happened to us when we changed ISPs.
So it's important to know what private network addresses the router is set to use.
So the very first thing I would do is set a machine to DHCP see what IP it gets assigned. Then you will know the private network addresses the router is set to use.
