"No route to host" means that your site is unable to make a connection to Facebook's servers. There's not a way to fix this within JFBConnect. It means there's either a server issue (DNS lookups are failing or a firewall is blocking outgoing connections) or a host/ISP issue (similarly a firewall, misconfiguration or some sort of blocking).
I'd contact the hosting company if the problem seems persistent. There's nothing we can do in JFBConnect about this. Our code simply says "Connect to Facebook" and PHP/the server/the host has to take care of the rest.
I hope that helps explain,
Alex