'Go to Settings' > 'Additional Settings' > 'Battery&Performance' menu
Change settings in 'Battery&Performance' as below
STEP 1. Tap 'Manage apps battery usage' in 'Battery&Performance' menu
STEP 2. Select Couchgram in 'Choose apps' menu
STEP 3. Select 'No Restriction' in Background settings menu
STEP 4. Setup complete