Best answer by Jeff S
Welcome to the community. It looks like you're playing music directly from your iOS device. We're currently investigating an issue where non-Sonos AirPlay devices on your network cause streaming directly from iOS devices to skip and stop when your iOS device goes into auto lock. We'll update this thread when we have more to share, but in the meantime you can get the streaming going again by disabling AirPlay on any non-Sonos devices on your network, or by disabling auto lock on your iOS device in the iOS settings menu under display and brightness.
Another option is to sync your iOS device's library with iTunes on a computer, then set up a music share. This will allow your Sonos system to play your music when there are non-Sonos AirPlay devices on your network, even when your phone goes into auto lock, or leaves the network entirely.