[bitfolk] Port 10000 is closed

I'm planning to install software on my VPS, which requires incoming UDP
on port 10000.

My iptables is set to allow incoming udp on that port, but it remains
closed to the outside world.

I've set up a simple listener on port 10000, then tested using a web
service for port checking, and I've tested using telnet from two other
locations.

"Unable to connect to remote host: Connection time out", says telnet.

Have I omitted to do something I should have done?

Ian.