Home media server can't play

Have setup a Plex server on my local network - Ubuntu Server, latest release.

I can find it fine in my media apps, browse the categories, select music to play, all looks good, but as soon as I try and play anything, I get (in HEOS): “Unable to play media. Please try again later”., and in BubbleUPNP, just never starts playing.

I have probably stuffed up the config, but not sure…

Thanks.

Do you have the same issue using any of the Plex apps or Plexamp?

Sorry, yes I am an id10t!
Rebooted the server - all good!

Thanks.