It indeed happened that the default GW provided on various network interfaces was the router that we do not want to be the GW.  In our case the OpenWRT Raspberry Pi 2 became the GW for any hosts dynamically getting an IP.  So all requests, were sent via the Raspberry Pi 2, which is not what we want.  To fix this, check your device if it is running a DHCP server:

root@OWRT01:~# ps | grep -Ei dhcp
  547 root      1240 S    /usr/sbin/odhcpd
 1556 root      1072 S    grep -Ei dhcp
root@OWRT01:~#

To disable this, you can do so in the Luci interfaces panel ( Luci -> Network -> Interfaces -> LAN ) then Edit then disable the DHCP server in the right most tab:

Save and restart the device.  

Cheers,
Tom