Long-time linux user here, but never really as my full-time desktop (Fedora 30).
I've tried Spotify from Flatpak and found the "Connect Device" list to be extremely unreliable, now basically useless (only shows the help, no devices). I have 5 SONOS devices in the house, not to mention other machines running spotify (phone, macbook) and the linux machine is the only one seeing nothing.
Client version is 22.214.171.124.gf614956d installed from LPF, Flatpak (latest, whatever # that is) also same behaviour.
I'm not even _exactly_ sure how Spotify conect works, I'm assuming some kind of avahi zeroconf UDP multicast thing, which if it were documented anywhere I ought to be able to debug.
AFAIK my machine is running no firewall, I have top-notch home network gear (Ubiquiti throughout), I'm in no VPN (although, I do regularly use one), I have no HTTP proxy congfigured, I have solid UPv4/6 support on my LAN/WAN and I have no idea how to diagnose this.
Any Linux experts able to suggest anything about diagnosing this with tcpdump and/or some network traffic inspection thoughts?