Unable to update Apple TV to the latest version

some carriers don't allow data on all ports some even only do port 80 (the web browsing port)

Apple TV: TCP and UDP ports and protocols used - Administrivia

TCP and UDP ports used by Apple software products - Apple Support

if that is your issue then you can bring the appletv to a wifi network to update it before going back to using it adhoc with your iphone

Okay, so the model itself is not part of the problem.

Please try updating while connected to a different network.

Else schedule a visit to an Apple Store or Apple Authorized Service Provider.

I can't update Apple TV to the latest version.

1. What is your model Apple TV box? Identify your Apple TV model - Apple Support Find your Apple TV model number - Apple Support
2. What is its current version system software?