HELLO.
i have a rb1100ahx2 running.

i have a T1 LINE 100Mbps. My ISP create a pppoe for this running on ether10
i have a back haul antenna that is connected to my isp. if the T1 line drops i get internet from anetenna around 50Mps
but to do this i have to set the pppoe to run on another interface ether5
when the T1 line goes up i change it again manually.

Is there a way to do this automatically ?

you can add 2 pppoe client, one for your principal ISP and other for your backhaul link.
In the routing table add 2 routes to 0.0.0.0/0, one with distance=1 for ISP and other for your backhaul with distance=2.

you can add 2 pppoe client, one for your principal ISP and other for your backhaul link.
In the routing table add 2 routes to 0.0.0.0/0, one with distance=1 for ISP and other for your backhaul with distance=2.

i cant do that. both the pppoe connect becouse they are in virtual lan and in routing table i have one 0.0.0.0/0, gateway a static IP from ISP