follow my steps To Fix Can’t Establish a reliable connection to the server/ Play store error
1. Make sure you have a ROOT ACCESS on your Device.
2. Install Root Explorer, Run App, Grant SU Access.
(if you dont have root explorer click here to download Root Explorer apk )
3. Browse root / etc… at the top of your screen you will see mount R/O and mount R/W…
4.Tap mount R/W
5.Look for host file, long press it and open with text editor.
6. just Add # (pound sign) on the first number.
#18.104.22.168(just one space)android.clients.google.com
SAVE IT and Reboot.
Now you can connect to Google Play very well.
Watch video How To Fix Play Store Error