Seems odd. I’d probably submit a system diagnostic in both situations, and call Sonos Support to discuss it. They might find the data in those diagnostics useful to pass on. 

If you phone has both a wifi and mobile signal it could be automatically using the mobile network for data if the wifi connection has an issue.

I had an android phone a while ago and if the wifi signal got too weak, it would stay connected, but switch all data traffic to the mobile network. On the screen both mobile and wifi icons were there. Restarting the wifi would usually fix the wifi connection.

When using a browser or apps which connect to the internet, you won’t notice apart from maybe being a little slower. For Sonos it will be an issue because the mobile isn’t actually sending data to your wifi network, so it can’t contact the devices.

There’s a couple of ways to test.

Depending how regularly it occurs, you could temporarily disable data on the mobile sim/network and see if your other apps on your phone also stop working and can’t connect to the internet. 

A less intrusive way is to use a site like https://ifconfig.me/ to get the IP address when you are on wifi and mobile. When the Sonos app stops working, check the site again and see which of the previously values it most closely matches. eg first 2 or three groups of numbers could be identical

It’s not a foolproof test though. Depending on your internet provider the address might change regularly so it’s harder to just say because it’s different that is what has happened. If the same company provides your internet and mobile they can also be similar.

Disabling mobile data and seeing if your phone stops working with the internet at the same time as Sonos is a simpler and more visible way.

Dear Mr. Sigh:

I have an Android phone (Samsung Galaxy S10e) and found a switch in Settings/Connections/Data Usage/Mobile Data that was on. I turned it off, as you suggested, and the Sonos app opens just fine! I opened a number of apps that use internet, and they seem to be working fine. My WiFi is also from T-Mobile, using a 5G gateway.

The only problem is I’ll have to remember to turn the Mobile Data on when I need it when away from my house or another WiFi network.

Thank you very much for your advice! Five stars!

Elliot

Dear Mr. Sigh:

I should have also mentioned that this issue only occurred with the new Sonos app, and otherwise my Sonos speakers didn’t seem to have any problems other than the Sonos phone app even when the Mobile Data was turned on.

Elliot

i have experience the same...sent them a diagnostic but it has happened since the fateful release of this aweful update.  I am hoping they fix it soon.  

Did you contact Support about the diagnostic? 

Support does not usually look at diagnostics unless they are contacted and asked to do so.

Don’t post the Diagnostic # here.

yes I did, more than once.  

While I don’t have access to an android mobile at the moment it may be possible just to prevent the phone using the mobile network as a fallback when on wifi, so you don’t need to keep remembering to switch it on and off. It varies between manufacturers if they support it and what they call the option.

The auto fallback means even though wifi is connected and may work, the device uses the mobile network data as it provides a better connection for the internet.

Samsung have rebranded some of their wifi behaviour as they changed the ui/android versions over the years. The setting is probably under the Intelligent Wifi naming now, but will be along the lines of a setting called “Smart Network Switch” somewhere in the advanced wifi settings.

I came across this guide which is for S10 android 9, so it doesn’t use the intelligent wifi branding, but the setting should be in a similar location.

https://userguide.one.nz/samsung/galaxy-s10-android-9-0/connectivity/turn-automatic-use-of-mobile-data-on-or-off/

That setting (or whatever it’s current name is) would let you keep the mobile data enabled on the sim and just stop the phone auto switching to use mobile data when you have a wifi connection.