.NET + React + MongoDB app sharing by traefic and docker

hello everyone
I have problem with docker and traefik

I have the application based on .NET react and mongodb

I run project locally in docker and it works

but I have problem with sharing this by traefik to subdomain.

I have some another application with React only and it works by traefik

my docker-compose

    image: flexbase
    restart: always
      - web
    container_name: flexbase
      traefik.enable: "true"
      traefik.frontend.rule: "Host:subdomain.mydomain.com"
      traefik.port: "80"

my Dockerfile

FROM microsoft/dotnet:2.1.301-sdk AS builder
WORKDIR /flexbase

RUN curl -sL https://deb.nodesource.com/setup_10.x | bash -
RUN apt-get install -y nodejs

COPY *.csproj .
RUN dotnet restore

COPY ./ ./

RUN dotnet publish "./FlexBase.csproj" --output "./dist" --configuration Release --no-restore

FROM microsoft/dotnet:2.1.1-aspnetcore-runtime
COPY --from=builder /flexbase/dist .
ENTRYPOINT ["dotnet", "FlexBase.dll"]

my traefik.toml

debug = false

logLevel = "ERROR"
defaultEntryPoints = ["https","http"]

address = ":80"
entryPoint = "https"
address = ":443"

endpoint = "unix:///var/run/docker.sock"
domain = "mydomain.com"
watch = true
exposedByDefault = false

email = "email"
storage = "acme.json"
entryPoint = "https"

  main = "mydomain.com"

address = ":8080"

and after go to the url I have Bad gateway

is an image wrong built? or maybe something with connection of mongo? or maybe something else?