You can disable the firewall on your LAN nic
HOWTO:
Stop Winroute Service
Go to C:\Program Files\Kerio\WinRoute Firewall
Open winroute.cfg with a TextEditor
Search for <list name="Interfaces">
Look up your Interface there and change <variable name="FirewallExclude">0</variable> to 1 so it would say:
<variable name="FirewallExclude">1</variable>
Save the config
Start Winroute Service
this should stop the firewall on the interface you put it to 1.
Warning:
Winroute will not firewall on that nic anymore so everything can go throug it.