I cannot activate iMessage and Facetime in my iPad and Macbook Pro

Hi everyone,

Last month, my iPad Air 3G (ran iOS 7.2) and my Macbook Pro (ran Yosemite OS 10.10), I could use iMessage and Facetime in both of them normally. But after upgrading iPad to 8.3, I can not sign in with my Apple ID on 2 devices anymore. It always has error: 'Could not sign in with your Apple ID. Please check your internet connection" when signing up in iPad and Macbook Pro.

I tried many ways: reset network, reset device... with iPad but it didn't work. Please help me. Thanks a lot.

Regards