That seems odd. Have you tried a simple reboot of that PLAY:1 by unplugging it from power for two minutes, then plugging it back in?

If that fails to clear the issue, I’d recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.

@CptAubrey,
Can you kindly clarify a couple of things…

Are the Play:1 units, that you mention, standalone, grouped, paired …or bonded to your Arc? It’s not clear from your post where it/they sit within your Sonos system?

As a first step… Are you able to play the station mentioned to the Play:1 speaker when it’s standalone, on wireless, or when you have it wired to the router? 

Are you playing from the Sonos App, or are you using Airplay from the Apple (native) Music App?

I have power cycle them as a first step. I’ll give it one more go and send the diagnostic. Thanks.

@Ken_Griffiths they are standalone. And I had never tried but they do play the radio episode when not grouped, interestingly. Adding the other speakers while the single Play:1 is playing works fine. Not sure how to proceed.

I’m playing from the Sonos iOS app on my iPhone. Everything is up to date. My Amp is connected via ethernet, the rest are wireless. All have static IPs. 

Assuming all are running on your routers WiFi and that you do not have any WiFi extenders, or other wireless access points, try simply changing the routers 2.4Ghz WiFi band to a different ‘non-overlapping’ channel - that’s either fixed channel 1, 6 or 11.

Also. if the router allows. set a channel-width of 20Mhz only, rather than a 20/40Mhz setting. If ‘anything wireless’ is near the speaker(s) them move the speaker one metre away from it and that should then improve its connectivity.

If problems persist, then just see if things work any better when you have one standalone Sonos product wired direct to the router (should not be a Home Theatre Surround, or Sub).

Another option is to group the devices starting with a different Sonos player, such as the Sonos Arc, or Play:5 and use either of these as the Group co-ordinator instead.

Hope that helps to sort things.

Ah I see our posts crossed and you have a wired Sonos Amp, then maybe start the group using that device as the co-ordinator. Also make sure that wired Amp is at least one metre away from the router it’s wired to.

I assume you are running all your products on SonosNet?… if so, just ensure your SonosNet channel is set in the App to a completely different channel to your routers 2.4Ghz WiFi channel. So if your SonosNet channel is set to 6, then set your router to either channel 1 or 11, for example. 
 

I am indeed on SonosNet. I also use Unifi with a few access points. But now looking once again I realized that while the APs were set to 20MHz on 2.4 and 40 for 5.8 all my APs were in the exclusion list. I have removed them and applied the changes. I’ll see if it changes anything. 

Here’s what’s considered to be a helpful/useful document link for those using a Unifi system with Sonos. Perhaps see if this might assist you too…

https://github.com/IngmarStein/unifi-sonos-doc

Most of those I had already set, but I did change the multicast and spanning tree settings. So far so good. Will keep an eye on it, thanks!