Firebase Realtime database Connecting issues from NodeJS

Question

I had the same issue in the production environment. Sometimes the node-js server(desktop application) does not connect to firebase's real-time database from starting(installing) then after a few days I try again and it starts working. I don't know what can cause this? I tried disabling the firewall, I have allowed apps through the firewall.

when these issues occur in the production environment I switch my database to MongoDB database it always works really well.

This happed first time on my own laptop today

I was starting a new project so I have written simple code as below but was not able to connect to a real-time database for some reason but no error!

var admin = require("firebase-admin");
var serviceAccount = require("./gerneral/service.json");
admin.initializeApp({
    serviceAccountId: admin.credential.cert(serviceAccount),
    databaseURL: "databseurl"
});
const db = admin.database();
var ref = db.ref("data");
const connectedRef = admin.database().ref('.info/connected');
connectedRef.on('value', (snap) => {
  if (snap.val() === true) {
    console.log('connected');
  } else {
    console.error('not connected');
  }
});
ref.set("it is not")

it output only ==> not connected

& not adding any value to firebase real-time database & no error

1. I have used mobile JIO internet (good).
2. I have disabled the firewall
3. I have double-checked the service account(JSON file) and database URL and rules of the database.

I have a different project(related to the firebase Realtime database) on my PC I run that project and it running perfectly fine.

what can cause this?

how can I solve this issue?

Additional Information: I try Using this project's database in other firebase-related projects (which is working fine). It shows this project's database connecting and getting data.

so this issue is most probably related to firewall or security but I double-check after disabling the firewall so why not connect to firebase's DB?

Please anyone how to find the cause of the issue?

Thank you in advance.