If enabled, perhaps see if switching off ‘Private WiFi Address’ in the iOS local network connection on the mobile, resolves your intermittent connection issue. See attached.

Thank you I tried that today didn’t help much same issue 

Might it be some other security software running on the phone like vpn/firewall or antivirus service or another thought is the iOS WiFi calling service maybe getting in the way.

FWIW …My Wife has an iPhone SE and I’ve just checked in the ‘About Box’ and is model number MHGP3B/A and she’s not having any difficulties connecting to the S2 Sonos system in our Home. She’s not seen the speakers disappearing etc. She has ‘Private Address’ switched off, no vpn etc. I’m just not sure if it’s the same phone model as the one you’re referring to?

My model MHGH3LL/A ….I will try switching off the private address again, but I don’t use WI-FI calling….does she have the 2020 version or the new version that came out in 2022

We can’t recall precisely when we purchased it - but around April 2022 so it’s probably the latest one that was available from Apple then.

Do you have a central-based WiFi router or a mesh based wireless network? Is your Sonos system running on your WiFi or SonosNet?

I just have regular router that internet company gave me, the phone is usually close by so running on WIFI

What you could try, even just as a temporary measure, is to wire one standalone Sonos speaker to your router, but set it away from the router (about a metre or more) and give the system a few minutes to switchover to SonosNet - the way to tell if every device has switched, is to look at the list of devices in the ‘About My System’ area of the Sonos App ‘Settings/System’ and check that each product has WM:0 next to them - if not, then power-cycle that device to make it switch.

Give everything 10 minutes to settle, and then see if the phone stops the ‘non-discovery’ of your devices and that they then always show in the Sonos App. 

See if that fixes it, because if it does, then it likely means it’s probably not the iphone, but more likely the router is not working too well with multicasting and discovery of devices across the different wired and wireless network segments.