I'm trying to set HTTPS-LB, which is not allow to use HTTP, on GKE with Ingress.

Now, as described in a official site, I deployed a simple application on a private cluster. This application works that can be accessed with a browser. ※both by http-connection and https-connection

Then I prohibit a http-access to the application by turning a frontend's protocol "http" off (deletion) in a setting of the LB. Actually, at first, a http-connection via the browser got error, not connection-error. After a 5-10 mins, http-protocol setting is restored automatically.

Here is a yaml file.

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: ingress-name
  annotations:
    # kubernetes.io/ingress.allow-http: "false" 
    kubernetes.io/ingress.global-static-ip-name: "ip-name" 
spec:
  #tls:
  #This assumes tls-secret exists.
  #- hosts:
  #  - XXXXXXXX.XXX.XXX
  #  secretName: ip-secret ← no use because of google-managed-ssl
  rules:
  - http:
      paths:
      # to app
      - path: /*
        backend:
          serviceName: XXXXX-backend
          servicePort: 80
      # to DS Export
      - path: /backend/*
        backend:
          serviceName: XXXXX-be-backend
          servicePort: 80

Is this problem due to a browser? or an internal settings like http-health-checker on gce instances?