No mention of network upgrade but port shown in diagram…
It’s saying the unit must be connected to your network; and that’s what the socket looks like.
Written by computer people for computer people, quite a few years ago - what could possibly go wrong…….? 
.
It confused the hell out of me when I used to update my SuperUniti, NAC-N 272 and UnitiQute 2 from Mac 
.
ATB, J