iTunes won't play offline

I have the family subscription to the iTunes streaming service and have previously been able to play my downloaded songs offline. Now all of a sudden I can't do this. I keep getting the dreaded "You are offline. Please connect to the internet" message. What is going on and how can I fix this. I do not get reception in my office and I am sick of listening to my coworkers' babbling. (My phone is an Android, Smasung Galaxy S 8.)