connect to the tivo service on both devices a few times. if the mini is stuck in the guided setup loop/you hit a dead end because it can't see the roamio, unplug the mini and go through the setup again. it will connect to tivo and if everything is right, it should be able to connect to the roamio.
Roamio Pro, wired ethernet
Mini using MOCA (from the Pro)
on Cablevision Raritan Valley system (Central NJ)
w/ Cisco PKM803 CableCARD on firmware 126.96.36.1991
*** 2013 newbie to Tivo ***