Subscription doesn't work with apollo-client and hot-chocolate .net core web api

I am working on graphql: Server is .net core web api and I am using Hot Chocolate as graphql server. Client is reactjs and Apollo client.

All queries and mutations are working fine. Subscriptions, however are not working. I am getting: WebSocket connection to 'ws://localhost:5085/graphql/' failed:

I have cors policy set in .net core:

builder.Services.AddCors(options =>
{
    options.AddPolicy(name: AllowSpecificOrigins,
                      builder =>
                      {
                          builder
                          .AllowAnyHeader()
                          .AllowAnyMethod()
                          .SetIsOriginAllowed((host) => true)
                          .AllowCredentials();
                      });
});

When I test in https://eat.bananacakepop.com/ it is working fine and I am getting data.

This is client code:

const httpLink = new HttpLink({
  uri: 'http://localhost:5085/graphql/'
});

const wsLink = new GraphQLWsLink(createClient({
  url: 'ws://localhost:5085/graphql/',
}));

const splitLink = split(
  ({ query }) => {
    const definition = getMainDefinition(query);
    return (
      definition.kind === 'OperationDefinition' &&
      definition.operation === 'subscription'
    );
  },
  wsLink,
  httpLink,
);

const client = new ApolloClient({
  link: splitLink,
  cache: new InMemoryCache()
});