Currently ALL newer flagship models are affected by delayed notification issue for at least past 6+ months, which started happening after around may 2018. Most devices are affected such as: S7, S8, S9, Note 9 and similar.
This is related to "doze" feature of android phone, where samsung optimization whitelist options are not working correctly thus affecting almost all samsung phones.
The issue is reproduced during following scenario:
1. User locks phone, waits around 5m
2. App sends notification (which is not marked as PRIORITY in google push services).
3. User does not get notification
4. User unlocks phone, and suddenly multiple "delayed" notifications arrive.
Multiple users has reported the issue and tried various workarounds such as:
- Disabling battery optimization for certain apps
- Disabling all battery optimization options
- Making sure "WIFI" connection is always maintaned, even during sleep mode
- Making sure DATA connection is always maintaned
- Restoring device to factory
- Totally replacing devices with new ones.
- Wiping cache and similar
There is currently only one temporarly solution working, which is disabling doze using adb console. This workaround is temporarly and works until next reboot. It requires setting phone to debug mode and connecting to it.
"adb shell dumpsys deviceidle disable"
Samsung is totally ignoring the technical issue since at least 6 months or more. There are multiple threads all over the web about such problem existing. Examples:
The issue is making phone totally unusuable for people who rely on instant notifications, such as alerts related to financial services like declining stock rates and similar. I dont understand why such critical thing like delivering notifications in time is totally ignored by samsung. The issue is not present on any other android phones.
If you have ability to contact someone of samsung development team, please forward this thread to make sure there will be finally reaction. Please reply to this thread if you have same issue.
I do it all in one package. And its work
1. Hard factory reset
2. Use a new google account to running device
3. Special access>optimise battery usage. Turn off notification which not response or delayed to APPS NOT OPTIMISE
4. From apps menu. Choose notification which is not running. Click and find mobile data. Turn on allow app while data saver on
5. From notification menu. Find recently sent. Turn off (sms) or blocked message
May it help to all. Thank you