I am streaming , how can I play music when provider goes down.

I think a good ukulele is clearly the answer...easy to learn some chords and play anything including hip hop and EDM. Ukulele EDM? Nothing quite like it. Impress your friends with your resourcefulness and remember, you can buy one hell of a uke for whatever your internet based hifi cost.

Xfinity - goes down more than a $20 hooker on payday. That is an intentionally crude statement in hopes Comcast might realize how embarrassingly poor their service level is.

Our xfinity service is quite good. It must be where you live that determines the quality of service. 

I have had the same issues due to Roon's regular and sometimes prolonged outages. I have a BluSound Vault that has my 1000 cd collection loaded into it that though on the network is controllable via my phone and I'm certain I've used it for playback when the internet or Roon are down. 

I haven’t read all the posts here, but hopefully someone has mentioned connecting the server directly to the streamer.  If that isn’t possible then put some files on a flash drive and play those through the streamer if it has a usb input for flash, or consider getting a portable player with storage that you can plug into the main rig .