tinc - Oct 2011 - client slow or never reconnects to different second address of server.

i have roaming TabletPCs that i would like to connect within the LAN
and outside the firewall.
The "server" is our main firewall and has two addresses, a 70.168.x.y
public IP and a private 192.168.2.1 both listening at the same high
port number.
The tinc clients connect fine when connecting from home or elsewhere
outside the LAN.
But when behind the firewall on the private LAN, the TabletPCs get a
192.168.2.Y address but still try to use the 70.168.x.y public IP
instead of talking directly to 192.168.2.1.
Is there some setting to increase the aggressiveness of checking for
connecting to the 192.168.2.1 ADDRESS?
What else should i do?