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

I'm a network engineer/architect by profession,  just wanted to get that out of the way.

The easiest answer to your question,  your internet provider connects through your WAN which is external to your local network,  LAN. Even if your WAN is down you should still have access to your local resources, ( music server). Unless your software needs to see an external WAN heartbeat,  you should be able to access your locally stored music..

@audioman58 I see several people have already answered your question.  You need a streaming server that does not require an internet connection like Roon. My setup is simple,  I only stream in one location,  my dedicated music room. I use a Cambridge Audio CXN V2 to stream Qobuz. I also have a 1TB drive that is connected to the USB port on the back of my Streamer.  If you are looking for whole house streaming,  you will need a music server with Endpoints.  As I stated earlier, there are tons of solutions mentioned in this post and defer to those since I only stream in one location.  Hopefully you've gotten the info from here.

Enjoy the Music..

@audioman58 , gowanus mentioned getting the Eversolo which is all the rage right now. Comes in 2 flavors: $700/1300 which I believe is a great deal for what you get. You can plug in your USB drive until you are able to get a drive that installs directly inside the streamer. With this type of unit, you don't even need a network to play your tunes. DAC/ Preamp/Streamer all in one. Your current drive may be able to install inside the streamer.

Enjoy the Music 

@audioman58 I can't comment on that. My digital set is simple.  Cambridge Audio CXN V2 and i connect a 1TB USB drive for local music.  Never a problem. If you are listening to music in one location and don't have a need to stream video around the house IMO a server or NAS is overkill.  You need an appliance that can connect to the internet to stream Qobuz,  Tidal  etc and play music from your local collection.  I believe in KISS.. If you want something more elaborate,  there are tons of suggestions in this thread. 

Enjoy the Music