Interesting detail that the guys at iFixit completely missed when they made their well-known "teardaown" from the Cupertino company's set top box. It looks like this Apple TV 4k add a hidden Lightning port in the ethernet connection port.
The user Kevin bradley, was in charge of discovering this port in the devices and possibly it would be one of the options that Apple has to be able to carry out tests or add firmware to the devices. In any case, the port is there and until today no one has seen it.
- kb (@nitoTV) 17th October 2019
This is now understood on the Apple TV board itself. In any case, it is not at all clear what the port is for and whether it will be officially "uncovered" by Apple in a new version of Apple TV. What is clear is that access to use is complicated and you can't think of connecting anything there at the moment. We also do not recommend any user to try to connect anything to that Lightning.
Apple has a long history of hiding ports in its products to use them practically exclusively for technical service, diagnosis and support, without going any further we have the well-known port of the Apple Watch that is located in the slot in which it is they insert the straps. A curious detail is finding hidden ports in the devices but, as we say, has accompanied the firm's products for quite some time. No more thinking about it, surely it is port used for Apple TV diagnosis on the company's SAT.