You have a TiVo BOLT, Roamio Plus/Pro, or Premiere 4/XL4/Elite that is in a different room from the router and/or doesn't have access to an Ethernet connection.
You have 4-tuner Roamio, a 2-tuner Premiere Series, a Series3, HD/HDXL, or Series2 DT. (You will also need a MoCA Network Adapter at the DVR.)