Android slows down foreground service response during sleep

Question

I'm testing my app foreground service, who should notify me, when it gets a response from "server/website" (Handler + Runnable every 7 sec checks for changes on server), and I noticed something unusual, when the phone is in sleep mode: At first, in the first minute, all seems to work fine, but afterwords, the service it seems delayed. It gives me a response after a minute from the server change,then 2 then 5, even 8 minutes. Then again 1 minute ... an so on

This is only happening when the phone is not connected with the laptop. I've tried to debug it with android studio but, when it was connected (with the data cable) to the laptop, all worked fine.

It's like it stops giving the app access to internet. And I'm saying this because when I get a notification from WhatsApp, I'll get my app notification as well.

Can android slow/throttle the internet access to the app? Or is there another problem that I'm not seeing?

I use two phones: Asus Zenpone and a Samsung Galaxy a5. The Samsung seems to work a little better, but ...

Answer 1

I managed to solve this problem with a solution from android developers docs:

https://developer.android.com/training/scheduling/wakelock

In the service class:

    PowerManager powerManager = (PowerManager) getSystemService(POWER_SERVICE);
WakeLock wakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK,
        "MyApp::MyWakelockTag");
wakeLock.acquire();

In the manifest file:

<uses-permission android:name="android.permission.WAKE_LOCK" />