Set the Wireless Mode to 2

I hate to say it, but it’s very likely the issue is related to your router when it comes to Sonos. I’m basing this on what I’ve read here about BT routers and their compatibility with Sonos systems. Sonos surely has user data on BT routers and any known issues, so it’s surprising they weren’t able to guide you through this more effectively. This is definitely an area where they need to improve, as so many people are still experiencing hardware problems—even after contacting Sonos support—and the one constant is that they’re all Sonos owners.
 

Thanks both - I have made that mode change as I’ve spoken to the support and it did work better (not great) for awhile. It was also an issue under the Vodafone router and the main ERA 300 is literally 1 meter away from the router but I just preserved. 

Not pfSense as such, that was simply my example, the same issue/fix is mentioned here for a variety of routers.

Making it even more fun, some routers work for some people while the same router has issues for other folk.

Everyone involved, customer, installer or Sonos would love to know why so we could have a fix instead of a work-around.

A meter distance is usually good, much closer and you can start seeing "too much signal" type errors.

​@Alxinchains 

At this point your only solution is to factory reset your speakers.

1. But before you do make sure your network hardware and device with Sonos app are up to date. 
2. Delete the Sonos app from your device
3. Now factory reset your Sonos speakers (this process will also erase any saved playlists)
4. Make sure all devices are blinking with a Green LED
5. Reinstall the Sonos app
6. Select “create a new system” (You can use your same email)
7. Add your products 1 x1 giving each a separate distinct room name (do not create any stereo pairs at this time)
8. Hopefully, you can see each product in the app
9. Now you can create stereo pairs; if you like

I reinstalled the Sonos system, but I'm pretty sure there's a bug in the app again... Some speakers only connect after multiple resets, it takes a long time for the app to load, it says "no product found on network" and then they appear again, but components randomly disappear again and reconnect after a long time. This is not a quality update!!! It seems that Sonos's development of the stable operation of the app cannot keep up with network or technical developments. Something still doesn't work properly after updating the app, you have to wait for one or two updates before the problem is solved. I've been installing and configuring B&O, Control 4, smart home, security system, internet network, Ubiquit, Sonos, etc... systems for years. I've never had so many problems with the app with any system that works with an app. Not even after the updates. I didn't have to go back to the customer because "the system disappeared or didn't work properly" on the network. It's happened several times with the Sonos system and it was always due to an application update, not the network settings... but I'm not surprised, this has been happening with Sonos for years, I just keep trying, so if it's changed, I always have to wake up and realize that nothing has changed, it's just gotten worse...

I've done this only a month ago, i shouldn't have to keep doing this. I don't have any stereo pairs.

I am in the same spot as others posting here.  Systems worked great, until this update.  Now nothing works.  Desktop apps tell me theres a firewall issues (which there is not) and iphone app will open, but never connects to anything.  This update basically killed my entire system.  Saying its my home network thats the problem is a cop out because Sonos refuses to address that they have only gotten sloppier as time goes on and push out garbage updates. So all we can do now I guess is wait for Sonos to realize they have a major bug in this update and push out a hotfix. 

Just look at the Google Store reviews, we are Legion!