asg is not only picking up forwarders from the pppoe with the default gateway.
I'm using isp manitu with a static ip (not the default gateway) and isp dtag (default gateway). What now happen is that the dns servers offered by manitu are placed as the first & second choice because they have a lower ip but they will never be reached via isp dtag.
1.) plz set the dns server learned via the default gateway before any other
2.) if you allow to learn dns server via different interfaces then please add automatically a policy route for those which are not reachable via the default gateway.