Getting "failure to get a peer from the ring-balancer"

[rookie-fpc]

Kong Gateway Version: 2.8.x
Kong Ingresss Controller Version: 2.12.x
K8S Version: 1.28.8
I am getting this error: "failure to get a peer from the ring-balancer"

httproute yaml:

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
name: ollama-route
namespace: ollama
annotations:
konghq.com/strip-path: 'true'
konghq.com/preserve-host: "true"
spec:
parentRefs:
- name: kong
namespace: kong
hostnames:
- "ollama.example.com"
rules:
- matches:
- path:
type: PathPrefix
value: /*
- backendRefs:
- name: ollama
port: 11434

backend service type is cluster ip and checked can be accessed in K8S

I checked router and upstream, seems KIC creater two rules with one router. But my Gateway just have one pod. I don't know if that has anything to do with it.

Is there anything advice? thanks