Open an external port into Istio - problem only on docker-for-mac
You have to define a VirtualService to specify where (to which microservice) the ingress traffic must be directed, see https://istio.io/docs/tasks/traffic-management/ingress/#configuring-ingress-using-an-istio-gateway.
Also try to send the Host header with your request, e.g. with curl -H Host:my-service.default.svc.cluster.local.