It could be wifi interference, or it might possibly be a duplicate IP address issue. If the information in the FAQ doesn’t fix it, try unplugging all of your Sonos devices, then, while they’re powered down, reboot your router. Give the router a couple of minutes to come back up, then plug your Sonos devices back in.

Do not do any factory resets.

I rebooted the sonos yesterday and the router and it worked temporarily. now it isn’t working! 

I have changed the channel to 11, but it still doesn’t work. I will look into changing the devices on my modem… I will see if I can set the channel on my modem. Does this seem like a reasonable approach?

Could you tell what to do if it is a duplicate IP address issue?

It’s the things I explained after the link to the FAQ, starting with my second sentence. It will be a ‘temporary’ fix, IMHO, any router that slips into a condition where it hands out duplicate IP addresses once seems likely to have the potential to do it again, eventually. May not be soon, though.
 

But the more permanent way to avoid that potential is to assign reserved addresses in your router. A bit daunting at first blush, but after reading the router’s manual, and doing the first one, it’s actually not difficult at all. 

I had this issue happen to me this week. I tried all of the reboot router, reboot speakers, re install apps, try from windows machine, try from Mac machine. The only thing I have managed to get a result with is resetting all speakers ( Hold the play and + button when you are plugging it in ) and setting up the system as a new system on the app…. Then Spotify appears and business back to normal. Having used this for over three years this is the first hitch that I have had.. Non technical user.. ope this helps

To anyone reading this thread, please ignore the advice of bkingdom11 above. A factory reset is never going to permanently help with an issue like this, instead share details on the forum and avoid factory resetting anything Sonos, ever (unless you just bought used equipment).

Controlav.. if you have an alternativesolution that works please share it. 

I did, I said ”instead share details on the forum“, and we can probably conclude its a wireless interference issue. However without actual details, and especially without a diagnostic code, there’s isnt a lot apart from the general KB article that Bruce shared can be provided.

I have been experiencing the "unable to add songs to queue” with Spotify since the iOS 14 update. Spotified plays just fine in my car and other portable speakers. Seems to be limited to one playlist. I can manually play one song in the playlist but it won't go ahead and play the entire playlist. Sent diagnostics to Sonos after “fixes” failed. When that didn't work, they gave up.

Help!

I have the exact same issue. I’ve spent so many hours trying to get around the bugs in Sonos’ app. I’m about ready to sell the whole system and try something else. I have a very expensive set up that I can only use half the time. I would not recommend Sonos to anyone because of their software issues. 

Sorry to hear about your frustration. Mine continues as well and Sonos has remained radio silent. Kept hoping that the patch updates would correct, but still a no go. A workaroundi came up with was instead of launching the playlist through Sonos, I do it through Spotify and connect to Sonos. Only did that once and not as clean. Would need to go back in and confirm.

Good luck!

I have a library of almost 4,000 songs and think I found a solution. I had a Spotify Playlist of all my liked songs. In the Sonos app, i used the option to take that Playlist and "Make a Sonos Playlist". Now that it's a Sonos Playlist vs a Spotify Playlist, I no longer receive that error message. Give it a shot.