It sure sounds like the device is not properly connecting to your router, and receiving an IP address. Doing a factory reset has only obfuscated the issue, and erased any previous information that might have helped Sonos help you. 

I would recommend that first you unplug the Beam from power, then reboot your router. Once the router has recovered, connect the Beam to the router with an Ethernet cable, and power it back on. You should hopefully be able to add the Beam to your Sonos system again.

Sonos does have 24/7 support via Twitter if calling in isn’t convenient for you. Click on the ‘Contact us’ at the bottom of this page for additional details. 

Thanks for the suggestion, but I tried all those things before, with the exception of plugging into Ethernet.  I just tried a all that again in the order in which you specified, and the app doesn’t even detect a product now, where before it occasionally did, it just wouldn’t recognized when I pressed the join button.  

My router is functioning well with all other connected devices, and I haven’t made any changes to my router or added any new devices since the Sonos was last connected successfully.  Just one day, poof! No connection.

I don’t use Twitter, and since it seems like Sonos isn’t responding directly to their own support forum, I guess I’ll have to call in.

Well this is very curious - after multiple attempts to connect to the Sonos as both a new and existing device, powering down, plugging into Ethernet, and a full 15 minutes after my most recent unsuccessful attempt, it responded when I gave a command to one of my other Alexa devices.  And upon opening the app, everything seems to be back to normal; I can control volume, my Truetone profile is applied in the app and clearly working, it’s available as a network speaker, and all is right with the world.

As uncomfortable as I am when technical issues mysteriously resolve themselves, at least I don’t have to sign up for Twitter.

Well this issue reared its head again - one day the app was recognizing the Sonos Beam, and the next day it doesn’t recognize it at all.

My phone is connected to the same network as my Beam; the only change I’ve made to my WiFi was to add a second mesh network, with a totally different SSID.  But that was several weeks ago, and things were working fine up until tonight.  

The speaker is connected to WiFi just fine, in fact - I can hit the play button and it resumes the last music stream I had been playing on it, and it responds to Alexa commands just fine.  But the Sonos S2 app is not recognizing it as either a new or existing device, even after unplugging and replugging the power cord.

Curiously, my Alexa app shows this device as “Online” but when I go into the device settings in the Alexa app, it shows “Network Error - Tap to Retry”.

I’m about out of patience with this.  The perceived convenience of the Sonos architecture isn’t worth much if it drops from the app expectedly.   In fact I had been thinking of getting some Sonos surrounds, but with these issues, I may just relegate this to the kids room and get something that just works.

I seriously can’t be the only person having these issues...someone pretty please help! 

FWIW, here are some screenshots showing the speaker detected by Alexa, but also showing the network error: