No push notification received when in standby mode under H3G provider
I bougth this phone two days ago. The android version is 4.4.2 and it is H3G brand (Italy).
When the phone goes in standby, after 10 minutes having locked the screen, it is not able to receive any notification from Gmail or Whatsapp or similar apps... anymore.
When I wake up the phone by unlocking the screen, it receives all the notifications I expected to receive.
I did several trials trying to discover the cause of the problem, and I find out that changing the SIM card (of another provider), the phone works perfectly. So, I went in the shop and asked for a new SIM card, thinking the problem was related to an old SIM card I got.
But this did not solve the problem. I am getting crazy and it was suggested to take the unit for repairing it, but I do not thinks the mobile is damaged...
Please, any suggestion that can help?
Thanks a lot in adavnce,