What Apple update? I’m on 13.5.1 and it’s fine. Try restarting your phone and also uninstalling and reinstalling the app. 
However intermittent sound is far more likely to be an issue with your home network. The phone is just a remote control for your system and doors not feed the sound. 
In which case try a ripper and device restart. 
https://en.community.sonos.com/troubleshooting-228999/tips-for-common-sonos-problems-6815645

Yes update was 13.5.1

following this update the Sonos app on my desk top on both phone and IPad is longer black but grey.

not tech savvy and need help!

Have uninstalled app and reinstalled but no chnage

Try unplugging all Sonos devices from power, then reboot your router. When the router comes back up, plug the Sonos devices back in to power.

Much like bockersjv, I’m using 13.5.1 on three different devices, and have no issues with my Sonos. 

Thanks for advice.  Have unplugged and rebooted router but still no go. Not sure whatelse to do

Contact Sonos Support directly to discuss it.

I suggest the phone folks, they have more options available because they're on the phone with you, they are available Monday through Friday during business hours. The Twitter support folks are available 24/7.

I had the same issue and tried a few suggestions from above, but none of them seemed to work.  So I decided to follow my on geek advice and began with rebooting my iPhone, and then went around and physically unplugged each and every Sonos device.  Yes it was a pain in the @ss...but everything now works.  Did not have to restart my router.  I think I’m going to install WeMo switches or some other remotely controllable plug option for everywhere I have a Sonos device.  That would make it easier than walking into every room and moving furniture to get to plugs.

I got the same issue right now the speakers even struggle to get synchronized together on stereo on a local source, Airplay doesn't  work to 

I got a android phone on the side and with the music played from the phone its works 

Hi @bouffegranny.

Thanks for reaching out, I’d be glad to help.

If the above advice was followed and it doesn’t help, please submit a diagnostic report through the Sonos app when an issue occurs and reply with the confirmation number. I'd start by reviewing your system and see if there’s anything causing this issue.

Alternatively, you can give us a call and work with a technician in real-time, they'll start by checking your system health and go from there. They have more resources and tools available for advanced troubleshooting.

If you have any other questions or concerns, don’t hesitate to reach out, we’re always here to help.