DHCP not working through Full Transparent config, cant browse to ADSL modem

Hi all :)

So I have configured my UTM with three NICs which is running behind a TPlink ADSL modem. The modem is acting as the DHCP server.

Clients on the LAN are not getting IPs from the DHCP on the modem.

I can browse to the internet if I set a static IP on a client but even then I cant browse to the ADSL modem.

Whats the fix??