This is a new thread on a topic that was previously marked as ANSWERED but for the life of me I couldn’t find it!

My iPhone app happily connects to my SONOS system, as does my MacBook app. However, my wife’s iPhone could not find our SONOS system on the app from her phone. I did all the recommended actions   like rebooting the network etc. to no avail. None of the iPhone settings like private relay, blue tooth connectivity, LAN connection came into play. Our two phones are configured the same way! I even removed the app and reloaded it without success. 

In the end, I removed the app from her phone once again and power-cycled the phone. Then I reloaded the SONOS app and it worked. I could speculate on why this worked but I would just be guessing.

If this works for you, I’m glad I could help.