aws linux server crashing after deployment

Question

I have been running my reactJS website for about one year so far and there's server crashing happened(this start to happen in the last 3 months) when each time I did a deployment(after doing the deployment it works fine but) & on the next day morning when I tried to log in to my website I couldn't access it & I have to restart my PM2 server to make it work again. but from last week my whole AWS instance crashed & I can't find why that happened, from last week this happened to me 2 times. then I have to go to AWS web and restart the server(before I have started using the console but since now I couldn't access it via console have to go to the AWS web and start it again).

also when 1st-time server crashing happens I got that my MySQL server closed the connection since I got it from the logs:

db error Error: Connection lost: The server closed the connection. at Protocol.end (/home/ubuntu/CIAO_ERP/node_modules/mysql/lib/protocol/Protocol.js:112:13) at Socket.<anonymous> (/home/ubuntu/CIAO_ERP/node_modules/mysql/lib/Connection.js:94:28) at Socket.<anonymous> (/home/ubuntu/CIAO_ERP/node_modules/mysql/lib/Connection.js:526:10) at Socket.emit (events.js:215:7) at Socket.EventEmitter.emit (domain.js:475:20) at endReadableNT (_stream_readable.js:1184:12) at processTicksAndRejections (internal/process/task_queues.js:80:21) { fatal: true, code: 'PROTOCOL_CONNECTION_LOST' }

then I have used this solution :stackoverflow answer for handling 'PROTOCOL_CONNECTION_LOST'

then I handled that issue but still, a connection loss appears.

anyway, I'm attaching my connection handling and my server code segments to check whether if I did anything wrong!

SERVER.js

const express = require("express");

const cors = require("cors");

const { DBConnect } = require("./connection");

DBConnect();

const path = require("path");

const app = express();

app.use(express.json({ limit: "50mb", extended: true }));
app.use(
    express.urlencoded({ limit: "50mb", extended: true, parameterLimit: 50000 })
);

app.use(cors());

app.use("/api/users", require("./routes/api/users"));
app.use("/api/invoiceSetting", require("./routes/api/InvoiceSetting"));
app.use("/api/auth", require("./routes/api/auth"));
app.use("/api/appSetting", require("./routes/api/AppSetting"));
app.use("/api/StakeHolder", require("./routes/api/StakeHolderSetting"));
app.use("/api/warehouse", require("./routes/api/WarehouseSetting"));
app.use("/api/production", require("./routes/api/ProductionSetting"));
app.use("/api/purchasing", require("./routes/api/Purchasing"));
app.use("/api/purchasingTemp", require("./routes/api/PurchasingTemp"));

//serve static assets if in production

app.use(express.static(path.join(__dirname, "../..", "build")));


const port = process.env.PORTADDRESS || 5000;

app.listen(port, () => console.log(`listening on http://localhost:${port}`)).on(
    "error",
    (err) => {
        console.log(`catched error on listen & error is   ${err}\n`);
       
    }
);

here is my DB connection handling code

const mysql = require("mysql");
require("dotenv").config();

let portDB = process.env.PORT_DB;
console.log("PORT ENV VARIABLE:", portDB);
if (portDB === undefined) {
    process.exit();
}

var db_config = {
    host: process.env.HOST_NAME,
    user: process.env.USER_NAME,
    password: process.env.PASSWORD,
    database: process.env.DATABASE,
    multipleStatements: true,
    port: portDB,
};

let db = mysql.createConnection(db_config);

const handleDisconnect = () => {
    db = mysql.createConnection(db_config);
    db.connect((err) => {
        // The server is either down
        if (err) {
            // or restarting (takes a while sometimes).
            console.log("error when connecting to db:", err);
            console.log("& restarting");
            setTimeout(handleDisconnect, 2000); // We introduce a delay before attempting to reconnect,
        } // to avoid a hot loop, and to allow our node script to
        else {
            console.log("Connected Mysql DB!");
        }
    }); // process asynchronous requests in the meantime.
    // If you're also serving http, display a 503 error.
    db.on("error", (err) => {
        console.log("db error", err);
        if (err.code === "PROTOCOL_CONNECTION_LOST") {
            console.log(`err.code : PROTOCOL_CONNECTION_LOST appeard\n`);
            // Connection to the MySQL server is usually
            handleDisconnect(); // lost due to either server restart, or a
        } else {
            // connnection idle timeout (the wait_timeout
            console.log(`db.on("error") else called & err : ${err}\n`);
            throw err; // server variable configures this)
        }
    });
};



module.exports = {
    db: db,//this db is used to handling mysql queries 
    DBConnect: handleDisconnect,//this is used to start the db 
};

I would be glad if any help me to solve this server crashing problem or whole AWS instance crashing problem I'm facing right now :(