So.. I've spent all day trying to figure this out, tried serveral online guides but still no success.

I believe i am trying to do something very simple:
Connect my RB ver3 to my ISP(Telefonica Spain) via PPPOE.

The probelm I get is, I setup my RB,
ether1 DHCP-client
ether2-5 DHCP-Server for local network
PPPOE Client running on ether1.
The pppoe connection get establised and I can ping internet address from the terminal on my RB, but get no connection on the lan side (ether2-5)
Tried resetting the RB serveral times and starting the configuration from scratch, but every time is the same.
here is a few pictures of the conf pages if they are of any use, I await earglery to be put straight on this very simple configuration error, that I can't figure out!!!

You will need NAT/Masq rule

You will need NAT/Masq rule

Thanks for your help! you were right.
Spent all day figuring it out and got know where. Woke up the next morning and figured it out..
Seems to be the way my brain works.