Downloads keep disappearing...Help!!!

I can't  get an answer  anywhere.  I have been  through every  setting  on this tablet. Galaxy  Tab A 10.1 Comcast  assures me the issue is their  app, but they have all but given up.

We download  from our  DVR, take the DVR to work, turn the tablet on, get a message. No downloads  on this device. Come home..well there they are..no wifi..no downloads.  Thought that was the whole  point of downloading,  take your shows anywhere. 

I am beyond  frustrated  at this point.  Can anyone help???

Lori