Remember, the ‘network’ that Sonos is discussing is most likely the ability of the speakers to talk to each other, and not the ability of your controller device to reach your router, nor the speed at which your router reaches the outside world. Remember, most devices that aren’t Sonos only maintain a single connection to your router, and from there the outside world. Sonos devices also maintain a connection amongst themselves. 

My guess would be, based on your issues, that there is just enough wifi interference to disturb the slightly larger streams when you include the PLAYBAR in your play back. Have you tried wiring the PLAYBAR directly to your router? 

Until the Sonos Arc came out, I was running two PLAYBARs and never experienced this issue…which doesn’t really mean that much, since you are. 

Beyond reading the FAQ I linked, I would 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 network and Sonos system.

Hi Bruce, thanks for reply.

Hard wiring the playbar to the router isn't possible I'm afraid, router is down the hallway and playbar is mounted on the wall, although I guess there's nothing stopping me from buying a 6 meter ethernet cable I guess and giving it a shot but if it cures it then clearly it can't stay like that forever and besides, I've only just recently experienced this issue and I've had this same set up for over 10 years so I cannot see why it would all of a sudden need to be hard wired?

The error message that pops up on the app definitely says wifi connection error yet I run a wifi test and I'm getting great speeds.

I've also noticed (not sure if it's a coincidence but I think it's related?) that the app takes an absolute age to connect or disconnected a certain speaker from the group, it just keeps spinning the little wheel on the app and then a few minutes go by and all of a sudden the speaker you selected or deselect does what you asked of it.

It's incredibly frustrating because your always ahead of what the app is going to do in 3-4 minutes time so you get that delay 

Guys, sorry I may be leading you down the wrong track here.

After further investigation today I'm not sure if my playbar is actually the issue

What I've done today is linked each speaker one at a time with another speaker and what I've noticed is the issue only happens if my playbar and my era 300 are linked, no other speakers give me any issues and all my other 6 speakers can play fine when linked to either the era 300 OR the playbar, but not when the playbar and the era 300 are connected at the same time, they don't seem to want to communicate with one another in the smooth way they'll connect to every other speaker. 

This causes my app on my phone to run slow but as soon as I drop either the era 300 or the playbar out of the set up my app runs fine and steaming is great - why don't these two speakers seem to like each other????!!!

I purchased a 50 foot Ethernet cable for temporary connections…which has been sitting in a cabinet for years now, but it helped me figure out a problem, so it was worth it. Remember, you’re trying to eliminate possibilities, not necessarily keep a permanent thing. 

Another thing to remember is that your WiFi doesn’t exist in ‘a vacuum’. It is influenced by all sorts of things, some may not be in your control, much like when I had a new neighbor put a WiFi device that stomped over what I was using for SonosNet. Nothing changed from my side, it was an outside source of wifi interference. Things change in a network, not always able to be seen by you, from outside influences, to internal changes, such as updates to your router’s firmware, the Sonos devices, etc. There is no such thing as a static network, generally speaking. You’d have to make a huge effort to set up one, and it wouldn’t be smart, unless you were a company or government site. And even then, it requires monitoring, I’d think, and pretty constant at that. 

And as I said before, getting great speeds are measurements between either the measuring device and your router, or extending to a server somewhere outside your home. It is not necessarily measuring the speed to or between your Sonos devices. 

The extra time you mention does lend credence to either wifi interference , or a potential duplicate IP address issue. The diagnostic would be a good way to track that down, the hard data in it, read by a Sonos employee, might indicate which it is, or perhaps some other network issue. 

One thing I’d certainly try is to check to see if indeed there is a duplicate IP address problem. Unplug all of your Sonos devices from power. Once that is done, reboot your router. Give the router a couple of minutes to come back up, and then plug back in the Sonos devices. If that speeds things up, you were suffering from duplicate IP addresses (I’d assume your router suffered from something like a power brownout, or a spike), and it might be worth looking at the router’s manual and setting up reserved IP addresses for all your devices. It’s good housekeeping for any network, and certainly wouldn’t hurt. 

But remember, calling Sonos support after submitting a diagnostic is much more helpful than any response here, since our responses here can’t be based on hard data, like theirs are on the phone. We have to base our responses on our knowledge of networking, and the way Sonos works, without the support of the hard data. 

Thanks again Bruce for all your input, much appreciated.

I'll give the tech guys a call tomorrow and run a diagnostic test to see if they can pin point this issue down.

You might be onto something though with the duplicate IP because a few weeks ago we had a Airbnb guest switch off the google nest in the guest apartment at the side of the main house and once they realised they reset it but they said it took forever to get the wifi back up and running again for some weird reason, and now I come to think of it I believe that's around the time I think this issue might of possibly started. 

We have a main router which has one wifi name (which we don't connect to) and connected to that is a google mesh set up with a different wifi name (which is the one we connect to) so I'm wondering if something has gone a stray with the set up?

That sounds odd. And a potential issue, if both devices were providing DHCP info to the network. . The folks at Sonos should be able help resolve this. 

For folks considering a temp Ethernet run a flat cable is a lot easier to store.

Do not get ripped off for a $100 cable, one like these 50 foot for $10 will do the job, longer and shorter options too. You should be able to find lots more like this example.

https://www.amazon.com/Ethernet-Internet-Snagless-Connectors-Router-Black/dp/B06XXH72SZ/ref=sr_1_18?th=1