On the server side
Install ngrep
apt-get install ngrep
and start to watch the UDP/10000 traffic
ngrep -q 'is accessable' udp port 10000
On the client side
Install netcat
apt-get install netcat
and send a message to the server through UDP/10000
echo 'yes, it is accessable' | nc -u your.server.com 10000
Result
If you can see the sent message on the server side, this means that there is no UDP/10000 connectivity problem between this client and the server.