There are a few things to consider.
1) you need to be able to contact the CMS by IP address, short name and Fully Qualified Domain name. Open a command prompt and try the following commands:
ping -a <ipaddress>
ping -a <shortname>
ping -a <FQDN>
All should resolve to the same IP address
2) You need to have the port 6400 as well as the request port open on any firewalls between your client and your server machines. The Admin guide talks about client to server firewall config.
A test might be to try using telnet servername 6400 to ensure you can connect without a refused or blocked message of any kind.
Those are the usual suspects for this type of issue. Usually just updating the etc/drivers/hosts file to include the ip, shortname and FQDN will work.
Jb