Operation `mytables.insertOne()` buffering timed out after 10000ms
https://mongoosejs.com/docs/connections.html#buffering
Mongoose lets you start using your models immediately, without waiting for mongoose to establish a connection to MongoDB.
Try
Start your application only after DB is connected.
mongoose.connect(process.env.DATABASE_ACCESS,{ useNewUrlParser: true, useUnifiedTopology: true, useCreateIndex: true},(err) => { console.log(err); app.listen(3000,()=> { console.log("server.js"); })});