Problem with plugin cordova network Ionic V5

Now, I write code withe Network plugin and when I disconnected network in my device, i can´t see allert in console.

checkNetwork() {
let connectSubscription = => {
console.log(‘Estoy con internet’);
let disconnectSubscription = => {
console.log(‘Estoy sin internet’);

The problem is that i don´t know, where i should write there code, if in the constructor, ngOinit… Beause i want when press a button check if it have connection and when no connection active background mode.

Also, I tried write a service and constructor.