* KnacK grabs the remington 870 *problem solver* on the way out the door to work this morning....
I usually use something like
this, but the Remington may work just as good.
The other q2 master servers have nothing to do with this, they can be there or not, doesn't really matter. It is definately a NAT issue, and could be present in your firewall config or in the iptables of your box. The heartbeat script just adds the source ip:port whenever it receives a heartbeat (after it has ACK'd it). The NAT is doing all the magic to translate lan:27910 to wan:57937 and then it waits for dplogin.com:27900 and makes sure it gets the same return path back to lan:27910. UDP is stateless so your firewall waits for another dplogin.com:27900 but will time out. On its next heartbeat it increments to another unused port number.
Are you using a hardware or pc iptables firewall solution? If you can't figure it out feel free to turn on logging and pm me your ruleset and log.