Change backend request hostname different with frontend

Hi, all. I have a question about Host header modify, here is my scenes:
I use traefik with docker in my lab.
I have a container run sniproxy service with domain (backend:
and I want to use ,reverse proxy of in traefik frontend router.
here is my labels with sniproxy service:

      traefik.enable: "true"
      traefik.http.middlewares.imgv2auth.headers.customrequestheaders.Host: ""
     #traefik.http.middlewares.imgv2auth.headers.sslRedirect: "true"
     #traefik.http.middlewares.imgv2auth.headers.sslForceHost: "true"
      #traefik.http.middlewares.imgv2auth.headers.sslHost: ""
      traefik.http.routers.imgv2443.middlewares: "imgv2auth@docker"
      traefik.http.routers.imgv2443.entrypoints: "websecure"
      traefik.http.routers.imgv2443.rule: "Host(``)"
      traefik.http.routers.imgv2443.service: "imgv2443" "false" 443 "https"
      traefik.http.routers.imgv2443.tls: "true"
      traefik.http.routers.imgv2443.tls.certresolver: "le"[0].main: ""

whatever I enable or disable the following, it always report "did not include a hostname" in sniproxy service and return 502 error.

     traefik.http.middlewares.imgv2auth.headers.customrequestheaders.Host: "" "false"

anyone know how to set corrently?