dyndns.org domain in Clients.conf

["black devils" <asblackdevils@gmail.com>]

Hi,
I have created one hotspot with a openwrt router and chillispot. I use a 
remote server radius (freeradius) for authenticate users of hotspot.

I have inserted in clients.conf Ip of the router:

clients 
82.256.52.11 {
            secret = testing123
            shortname = test
}

With this configuration all working fine but unfortunately router has a 
Dynamic Ip therefore a can't use its Ip in clients.conf

Thus i try to insert a dyndns domain of the router in clients.conf

clients router.dyndns.org {
            secret = testing123
            shortname = test
}

but with my displeasure freeradius doesn't recognize client.

Same suggestions??

Thanks