Era 300 as stereo with turntable connected

Tried a new router with no luck. Same crap with the era 300 dropping out. Sonos support asked me to remove sonosnet. That has also been done with no luck. I don't think there will be anything left to do but return the era speakers. And the turntable.

You should have rebooted everything on the network after replacing the router. Then it is a good idea to “reserve IP addresses” on the router for all regular network clients, especially the SONOS units. You’ll need to consult the router documentation. This will be a one time boring task, but it saves a lot of grief over time. You’ll not need to repeat this task unless you factory reset or replace the router or change the client mix on the network. 

We cannot rule out a 300 hardware issue, but this is not high on my list of possibilities. SONOS support should be able to discover this.

I have given both 300 static addresses, but this doesn't seem to solve the problem. I notice that the right 300 drops out of the app completely. And I have to restart it to get it back in. I get the feeling of a hardware error, but I understand that it is most likely related to the settings on the router. I just can't understand why it should be so difficult to solve. Sonos support hasn't asked me to do anything specific with the router settings, which I find strange.

As a diagnostic step, “unBond” the stereo pair and exchange left and right. The left speaker becomes the pair’s “Coordinator”. All network traffic for the pair flows through the Coordinator.

Have you physically relocated the 300’s?

Yes, I have tried moving the speaker that is dropping out, with no improvement. Now I have replaced the speakers and set them up as a stereo pair again. Now it is the right speaker that plays continuously while the left one drops out. Previously it was the other way around. Eventually the right one also drops out - and then both come back as a stereo pair. In the meantime, I get a message saying that there are problems encoding the song, and Sonos skips to the next one. Registers that the right one (formerly left) prefers 2.4 Hz while the left one (formerly right) prefers 5.5 Hz. 

Edit: In the sonos app, the left speaker disappear often, and sometime the stereo-pair disappear. The rest of the system plays smooth. The problem is only with the new pair of era 300s.

I’m becoming suspicious of a hardware issue in the current left 300. What happens if you break the pair apart and use them as individual Rooms? I’d also consider alternately powering down one of these Rooms. Don’t Factory Reset either unit until asked to do so by Support because this trashes diagnostic data. In addition, there is another, even more detailed diagnostic level that can be invoked. I don’t think that level 1 agents can deal with this. Maybe you’ll be transferred to level 2 or 3.

I’m not overly concerned about the 2.5 or 5GHz preference because it probably is location determined, but keep track of this and mention this to support. The newest units are fairly docile about joining a network. I have two WiFi networks and the players are free to use either. If one network goes down for maintenance, the units will flip to the other without a fuss. (This must be setup with some care.) Make sure that your router is configured such that 2.5 and 5GHz segments can share traffic. This is a typical default, but it would pay to check.

I have now tested separating the speakers from the stereo setup, playing them separately - and together. Both play fine alone. When they play together it works fine for a while, but the same speaker (as always) fails again. When I create a stereo pair again, the app behaves badly and the same speaker fails again. It's hard to understand, but isn't it strange that it's the same speaker that fails all the time?

I’m even more suspicious of a hardware issue with that balky speaker. Since we don’t have access to the diagnostic data, you’ll need to work with SONOS phone support. As a test can you wire the problem speaker to the network? (You’d need the SONOS USB adaptor that includes network support to do this and I don’t think it is worth the trouble to purchase the adaptor just for this trial.)

Thank you ​@buzz . Now I've tried connecting the "problem speaker" directly to ethernet. It plays as a mono speaker, but now it no longer produces sound when I connect both in stereo. The same thing happens when I connect them as stereo when both are on wifi in the living room. Can we perhaps conclude that there is a fault with the speaker? I'll discuss it with Sonos Support.