The HPNA light is only on if a device is using that connection, usually a STB connected via coax (can be over twisted pair in rare situations like apartments). It sounds like your setup uses ethernet which would not turn on the HPNA light.
The previous scene is an excerpt from Brain on Fire: My Month of Madness, and just one of many hallucinations Susannah Cahalan experienced in 2009 during her month-long hospital stay, in which she was diagnosed with a rare neurological autoimmune disease, known as anti-NMDA receptor encephalitis.
36,074 pages on this wiki. Mama was a former patient at St. Gertrude's Asylum, known as Edith Brennan in the 1800's; her appearance and simple actions imply she had Down Syndrome, though this is never officially stated.