Getting to a gRPC service behind Traefik in K8s

Traefik Traefik v2 (latest)
,
1

Trying to evaluate Traefik for wider use, I am struggling with reaching my gRPC service running in my k8s cluster. I have - after some struggles - set up a cert manager, and I have set up the IngressRoute. I am getting a "'500 Internal Server Error' caused by: unexpected EOF" from the traefik logs, and nothing gets to my service. I see no errors in the dashboard.

apiVersion: traefik.containo.us/v1alpha1
kind: IngressRoute
metadata:
  name: whoami-grpc-route
  namespace: {{ .Values.environment.namespaceName }}
  annotations:
    traefik.ingress.kubernetes.io/router.middlewares: "traefik-v2-autodetect@kubernetescrd"
    traefik.ingress.kubernetes.io/service.serversscheme: h2c
spec:
  entryPoints:
  - websecure
  routes:
  - kind: Rule
    match: Host(`{{ .Values.environment.namespaceName }}.mydomain.com`)
    services:
    - name: whoami-grpc-svc
      port: {{ .Values.whoAmI.grpcPublicPort }}
      scheme: h2c
      passHostHeader: true
  tls:
    secretName: {{ .Values.environment.namespaceName }}.mydomain-tls

The service is defined like this:

apiVersion: v1
kind: Service
metadata:
  namespace: {{ .Values.environment.namespaceName }}
  name: whoami-grpc-svc
  annotations:
    traefik.ingress.kubernetes.io/service.serversscheme: h2c
  labels:
    app: whoami-grpc
spec:
  type: {{ .Values.service.type }}
  ports:
    - port: {{ .Values.whoAmI.grpcInternalPort }}
      targetPort: grpcs
      protocol: TCP
      name: grpcs
  selector:
    app: whoami-grpc

Any hints as to what I should be looking at? I have tried to search this forum, the greater internet in general, but not really found anything interesting.

Thanks in advance,