I read through all the posts in the link you posted. Have you tried the temporary fix posted in said link?
"sprmankalel 2 days ago
What has worked quite successfully for is the following:
Since the issue is not just when the device is connected to Wi-Fi but when the device's screen is off (standby) and connected to Wi-Fi. I went into the Wi-Fi settings, tapped the menu, headed to Advanced and changed the setting for Keep Wi-Fi on when screen is off to No.
Less than a minute after I turn the screen off the Wi-Fi disconnects and I get my notifications flawlessly. No, this isn't a complete fix but it does help."
Did this do anything to help your situation? I know it's just temporary, but hopefully this will work, at least until someone has another idea, or a fix is pushed out for this device.
S5 tap'n