[OnePlus 7 Pro Questions & Answers] vvvmilan:
Alright, here's another complaint about delayed notifications on OxygenOS, my OnePlus 7 Pro. Thing that really makes my phone unusable.

Please read the whole post so we can avoid tips like "aw, you can disable global battery optimizations in settings, also disable it for apps you want to get notifications for" because I have done everything found on threads as solution and nothing helped. Thanks.

I have tried to diagnose what the problem is in past few days as I saw that notifications on my phone aren't showing up at all. For ALL APPS, not only 3rd party. For NONE of the apps. Google services, Viber, Dropbox, Email, Instagram, 1st, 2nd, 3rd party apps.

I was reading about this problem on various forums found on google and first thing I discovered that this is mentioned as far as 2016-2015 which is very bad that such problem persists and isn't solved even in 2020.

Second thing, only solution I found mentioned as successful is "adb shell dumpsys deviceidle disable". That suspected culprit is Android Doze, light sleep, deep sleep. That doesn't work for me.

Found only one post came to similar conclusion as me, but unfortunately nobody answered it. Here's what I managed to find out as I tried everything.

In my case problem isn't at all in phones (deep) sleep, Doze, battery optimizations, apps getting killed in background, etc...

I'm not receiving notifications ONLY WHEN MY PHONE IS CONNECTED TO WIFI. It takes only few minutes from when I put my phone on a table to stop receiving notifications! I can track that when I'm using PC, receiving and answering messages on Viber - nothing shows up at my OnePlus. Even after 15-30 minutes, hours, notifications aren't showing up on phone. What makes it worse: I receive message on Viber, get notification on PC, (I'm not opening message on pc for ex. 20 minutes) take my phone, use other apps - STILL DON'T GET notification. Until I open Viber (or any other particular app) only then it connects, refreshes and show up new messages!

And no, it's not problem in Viber, I took it only as an example because it's my main IM app, as I said notifications for all apps aren't getting trough: GMail, Instagram, Dropbox, you name it...

Another strange thing is that Google won't automatically sync it's services while on wifi. For example Keep notes, Drive and so on. When I go to settings > accounts > google account - auto sync is enabled and in details I can see that every single service is updated LAST TIME I WAS ON 4G.

Viber backup also won't upload it's messages to Google Drive while on WiFi. On 4G it syncs backup without problems.

As I said, all of these things work flawlessly while I'm on 4G. All this syncing and NOTIFICATIONS as well. Only on 4G.

I even tried connecting to different wifi routers, 5 GHz, 2.4 GHz and it behaves the same no matter what I do.

When I take my phone, disable WiFi and enable 4G I immediately get all the notifications that were delayed while on WiFi. So that's how I got to the conclusion it is problem with wifi, not deep sleep etc.

Other than receiving notifications, I use phone over the WiFi normally, without any bugs or glitches: YouTube, Instagram, Chrome... Just (push) notifications aren't getting trough, and I can see all of them being refreshed as opening them.

OnePlus 7 Pro is updated to the latest firmware, 10.3.

Once more, please read the whole thread. I hope someone from OnePlus will read it and help me solve this problem as device like this is absolutely unusable.