Q: I have a generation 3 Apple TV box that I need help with setting up

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.

You might also try connecting to a different network and then trying again on your own, you might try at a friends or use the wifi hotspot on your mobile phone if you have one.

It sounds like you are setting it up for the first time. Check that your router is not blocking outbound connections on port 123, Network Time Protocol. ATV uses this to set the time.

If your Apple TV stops at the date and time screen during startup - Apple Support