Getting 404 if one of the kubernetes service configured in traefikservice doesn't have pods in it

I have two deployments named blue & green and also have their respective blue & green kubernetes service for it.
I have one ingressroute which routes to traefikservice.
In traefikservice i have weighted approach, here i added blue & green kubernetes service.
If any pods (may be blue / green) goes down then entire routing becomes down.
My expectation is whenever blue pod goes down, it need to route to green pod alone and vice versa.
How to achieve this in traefik ???