Explain how this device works

Question

Computer networks

They put the Internet into the house and put this:

Answer 1

This is a media converter . An optical fiber (yellow cable) comes to you, the signals are received by a phototransistor, restored, recoded and transmitted over a twisted pair. Likewise in the opposite direction.
It works, as a rule, at the first level of EMWOS, i.e. both at the input and at the output - Ethernet frames, only coded differently depending on the medium used (optical fiber or twisted pair)