1.Check wireless connection.
The first step of diagnosis have to any other device connected to the same network, ensure the wireless connection is working fine, or verify the settings of your wireless router to correct it.
2.Check your Keep Wi-Fi on during sleep Settings.
Owing to Wi-Fi sleep policy your Wi-Fi connection may be going to get disconnected every now and then.
Tweak this policy to keep your Wi-Fi connection awake.
[Settings] >>[Wi-Fi]>>[Advanced]>> Check [Always] to keep the Wi-Fi on during sleep.
Save changes and exit all the screens. Your Wi-Fi will never get disconnected again due to this policy.
3.Check signal strength of wireless connection.
The performance of a wireless network connection depends in part on signal strength.
You have to connect the Wireless network where the signal strength is strong.
Check Wireless network signal strength icons in notification bar.
4.Try to turn off/on Wi-Fi on the device.
First to turn off Wi-Fi, [Settings]>>[Wi-Fi] >>[turn Wi-Fi to off].
And then to turn on Wi-Fi, [Settings]>>[Wi-Fi]>>[turn Wi-Fi to on].
5.Try to forget network on the device.
Forgetting wireless networks allow your tablet/phone to reset some settings.
[Settings]>>[Wi-Fi]>>Press & hold your[Net Work Name(SSID)]for 2 seconds.
>>Select[Forget Network]>>Re-Connect your wireless networks if it's disconnected.
6.Try to reboot your device.
7.Make sure your firmware is up-to-date.
>>Select[Settings]>>[About tablet]>>[System Firmware Update]>>[Check Update].
8.Try to reset your device.
Note: once RESET was performed, all data, apps, settings and personal information will be deleted after initialization.
Third-party programs might be the major probability of Tablet/Phone instable, suggested to have a full reset for the device if the situation persists.
[Settings]>>[Backup&reset]>>[Factory data reset]
9.Try to other wireless connections.
If steps above were not able to solve internet connection problem still, please try other wireless connections if available, otherwise contact your networking provider to technical support.