NoRouteToHostException on client or server?

Basically it says that your client cannot connect to the server due to the address is inaccessible from the client machine.

Please check that the address you are connecting to is accessible, either via ping command in your Command Prompt (Windows) or terminal (Unix-based):

ping <address>

or if it's a web server you can try to check it in your web browser.
The ping command is helpful for me in most cases, since I would know why exactly I can't connect to the address. It can be a mistyped address or like the javadoc suggests, problem with firewall.

Either. It could be a firewall on the client machine blocking outgoing calls or somewhere at the other end.