@remlei:
vlans wont work, since im not using vlan on wan interface. its a untagged traffic. and all wan interface connect to same untagged traffic.
Well, that is completely broken idea as noted above, plus frankly, if those 3 PPPoE WANs are using the same gateway, you will just get an unsupported setup broken in various more or less cryptic ways, VLANs or not.