If i understood correctly, you have installed DS twice one on Server1 and second on Server 2. When you have two server scenario, you need to install BO CMS on one server and on other server BO DS. While installing DS on the second server, choose the CMS of first server.
You said DS did not recognize the CMS in server 1. Are all the ports open? Any firewall or anti virus? Did you try ping from one server?
Arun