Simple test would be to rsh into the router pod and use netcat to send a message.
$ oc rsh <router-pod-name>
pod> echo '<14> user test message from router pod' | nc -w 2 -u <node-host-ip> 514
And maybe try from the host (openshift-node) or another node as well.
$ echo '<14> user test message from the node' | nc -w 2 -u <node-host-ip> 514
And if you need to open the port you could use something like:
$ sudo iptables -I INPUT -p udp -s <router-node-ips> --dport 514 -j ACCEPT
$ sudo service iptables save
$ sudo service iptables restart