Hi recently subscribed to the Plex premium service and anything on my mobile works fine on Sonos. It's just music on my WD NAS won't work. If accessing the Plex app via the Sonos controller it works fine.
Any ideas? Assume it's a NAS setting rather than the app.
I suspect it’s an issue with your router and how it controls traffic to outside of your network. Even though Sonos and your NAS are both inside your network, I believe Sonos accesses your music via a Plex cloud server. You can confirm this with a simple test. Using the Plex app on your mobile device while connect to your home WiFi, test to see if you can play music stored on your NAS. Then disconnect WiFi on your mobile device, and see if you can playback music stored on your NAS while off the network. If the first test works, and the second test doesn’t, the issue has to do with your router/network rather than settings on the NAS.
I have similar issues, as I sometimes cannot access my local content via plex from Sonos or while outside the network. It seems I have a ‘double NAT’ situation causing the problem, which would require me to change my network in ways I’m not sure I want to do. I can usually resolve the problem temporarily by rebooting my Nvidia Shield (my plex server). It’s on my to do list to fix, but since it’s one of the not so fun items on my list, and I have a work around, it may stay on the list for a long time.