Configure external DHCP server with RT-N66U

[White_Knight]

I have a external configurated DHCP server on Synology DS.
On my router i have been turn off internal server.
With this configuration DHCP is working.
Today i try to connect wi-fi device to my Guest network, Device couldn't connect because can't get IP from server.
In guest network configuration i turn off access to my local network. I think because of this i can't connect to DHCP server and could not finish IP configuration.
Merlin , it possible to make DHCP requests not blocking by internal router firewall ? And make visible DHCP server to router Guest Networks?

 

[ColinTaylor]

Have a look here: http://www.snbforums.com/threads/passing-dhcp-requests-with-ebtables.15287/#post-103784

 

[White_Knight]

Thanks you for your help !
This solution is work .