question to advertisement discovery over public network

Hi,

I am running 2 jxta programs: 1 is publishing a newly created pipe adv. 
the other is searching for this adv.
When I run these programs with using "LAN discovery", eg jxta 
configuration set to : use a relay=true, broadcast=true,enable incoming 
connections=false
all runs perfeclty and the adv is found.

However when I run it using the public network, eg jxta configuration 
set to : use a relay=true, broadcast=false,enable incoming connections=false
It takes hours for the adv to be found.

Hoping that a group will reduce the discovery duration I defined a 
group. Both programs join this group and the adv is published within the 
group.
However it now takes even longer for the peers and for the pipe adv to 
be found.

Is there any way to speed up the adv discovery ?

Rgds

Ron