Cloud not reach Cloud Firestore backend on Angular

Question

some of my clients are facing to a trouble with this error

There are able to login on my website but this error occurs when a query is triggered to reach my firestore database. On my side I don't have this trouble.

I found some workarounds link 1 link 2 [link 3] link 44. It seems i need to add a firestore seeting like experimentalForceLongPolling

I tried something like this in my environment.prod.ts

    import env from './.env'; 
//ENV PROD
export const environment = {
  production: true,
  version: env.npm_package_version + '-prod',
  serverUrl: '',
  defaultLanguage: 'en-US',
  supportedLanguages: ['en-US', 'fr-FR', 'es-ES'],
  experimentalForceLongPolling: true, //THIS LINE

//Base de données 'firestore' and 'realtime database' from FIREBASE => BD PROD gbl-ist-ve-dlaaas
  firebase: {
    apiKey: "myKey",
    authDomain: "xxxxx",
    databaseURL: "https://xxxxxxx",
    projectId: "xxxxxxx",
    storageBucket: "xxxxxx",
    messagingSenderId: "xxxxxx",
    appId: "xxxxxxx",
    measurementId: "xxxxxx"
  }
};

and in my app.module.ts

@NgModule({
  imports: [
AngularFireModule.initializeApp(environment.firebase)
],
...
...

Is that correct way to import setting experimentalForceLongPolling ?