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.
But it was the death of young Heather O'Rourke, who played Carol Anne Freeling , that sealed the film's spooky reputation. She was misdiagnosed with Crohn's Disease in 1987 and died the following year of a heart attack as doctors operated on a bowel obstruction. She was just 12. Of course the series of events could be little more than tragic co-incidence but they have kept the spirit of Poltergeist alive.