Default When Wi-fi is enabled &device is idle/sleep, not getting emails & chat notifications

Hello Team,

I bought New S5 T-mobile Version. When my Wifi is enabled and the device is sleep or idle, emails, facebook, whatsapp and other notifications are not coming. I sent a test email from another device and whatsapp message from my friends device. I did not got any notification when my phone was idle. Once I press the home button or power button and unlock my device, immediately all the notifications are coming. I am not facing this when my mobile data is active. This happens only in Wifi. Tried in couple of wifi networks and the result is same.

After reading some blogs and forums, just typed *#0011# and made Wifi power saving mode off. But no use. Also changed the connection to Static mode and no use.

Request any one of you to help me.

Regards,
Muthu