Used to have issues like that at work because of flaky internet, I would lose connection to Google servers and thus push notifications. Usually just turning the screen on and waiting 5 seconds would make it reconnect.
Haven't had this issue since we got a mega wifi antenna that goes through walls...
Yeah that makes sense. But what's interesting to note is that it worked fine on my old LG Optimus T that had even worse WiFi connection. And the new phone is the only change in my home network.
Also it's not only when sleeping that the problem occurs. Notifications just don't come in at all period until I open the respective apps. Problem happens on other WiFi networks too. And also when I'm in my office only 10ft from the router.
All this leads me to believe that it is the phone or the ROM.
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