Samsung galaxy tablet 3 Lite internet connection problems Samsun

Hello, I have a samsung galaxy tablet 3 light the internet on it keeps shutting itself on and off it won't stay on I don't know why but I can use the Wi-Fi on my cell phone and it works just fine but when I asked if my tablet it will not stay on long enough the internet keeps shutting itself on and off I have tried rebooting my modem which is through AT&T and it seems to be working just fine but when it comes to the tablet the internet shuts itself on and off what can I do to fix this problem ASAP