My Apple TV cannot set the date and time even after having gone to network setting and choosing central time.

Assuming this is not the first time you have used your Apple TV

1. You might try restarting the Apple TV by removing ALL the cables for 30 seconds.
2. Also try restarting the router. (Also try removing it’s power cord for at least 30 seconds)
3. If the problem persists, try a restore, you may want to try the previous procedures several times before doing this.
4. If restoring from the Apple TV doesn't help, try restoring from iTunes using a USB cable.

If this is a new Apple TV, in addition to trying the above, it may also be that your network router is not allowing access to the timeserver, check that your router allows access over port 123.

what does this mean: check that your router allows access over port 123

It means that the port has to be open on the router, which is used to set the date/time. You will need to refer to your router's manual if unsure