istio gateway: getting Warning [IST0162] but can't finde what is wrong

Question

If anyone could give me a hint, it would be a great help! I am new to istio and would like to have the following setting: from my browser I send a https request to my local web page (a test page), then an istio gateway will forward this request to my nginx ingress (I use the one in minikube) and the ingress controller will send the request to a web server (node.js).

But the problem is: I get this warning from istioctl analyze:

Warning [IST0162] (Gateway default/istio-gateway-ingress) The gateway is listening on a target port (port 443) that is not defined in the Service associated with its workload instances (Pod selector istio=ingressgateway). If you need to access the gateway port through the gateway Service, it will not be available.

here are parts of my code:

    apiVersion: networking.istio.io/v1alpha3
kind: Gateway
metadata:
  name: istio-gateway-ingress  
spec:
  selector:
    istio: ingressgateway # use istio default controller
  servers:
  - port:
      number: 443
      name: https
      protocol: HTTPS
    tls:
      mode: SIMPLE
      credentialName: istio-gateway-certs
    hosts:
    - testpage.com


    apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: testpage-com
spec:
  hosts:
  - "testpage.com" 
  gateways:
  - istio-gateway-ingress  
  http:
  - match:
    - uri:
        prefix: "/" 
    route:
    - destination:
        host: ingress-nginx-controller.ingress-nginx.svc.cluster.local # geändert am 19.3.
        port:
          number: 80 

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: ingress-webserver
  namespace: default
  annotations:
    nginx.ingress.kubernetes.io/ingress.class: "nginx"
    nginx.ingress.kubernetes.io/proxy-body-size: "50m"
spec:
  rules:
  - host: testpage.com
    http:
      paths:
      - path: /
        pathType: Prefix
        backend:
          service:
            name: webserver-service
            port:
              number: 8001

Just in case it's important: I use minikube via docker on macOs m1.