Could you post the commands you use?
The error "No route to host" is a network issue. Nothing to do with nfs. My guess with the information you provide is that the default gateway in the client is not properly configured. Are they in the same network? Is the firewall (iptables) down in both machines?
The "connection refused" message is a good sign that the Server can connect to the client, but the client does not have a ssh service running, or it's configured to not accept connections.
Also, for nfs server, you need to properly configure the /etc/exports file... or similar.
HTH,
Pedro.