can I get the old app back?

Have you “reserved” IP addresses for all of your regular network clients? This is always good practice, even though your issue seems more like interference.

Are any of your SONOS units wired to the network? Obvious sources of interference would be Microwave Oven, child monitors, wireless video cameras, and SONOS units too close to the router. SONOS support should notice if one or more units is being buried in interference. Submit a diagnostic within 10 minutes of an event, log the diagnostic number, and call support.

Make sure that your router setting will allow data transfer between 2.4 and 5GHz bands.

No Reserved IP addresses

I’m familiar with the microwave ovens interference issue.
There’s no child monitors there’s no Wireless video cameras and the Sonos is not too close to the router except for the playbar. I use the ethernet cable between the router and the playbar.. 

Yes, I’ve done that with the customer Support at Sonos a couple of times immediately generating a log and giving them a call because I know it could be a while before I’m able to talk to my person. But no matter what is done the Various Random problems randomly comes back.
The router does allow data transfer between 2.4 and 5 GHz bands.

At least today it’s behaving itself.

​@RKP 

Oh, you didn’t mention before that at least one Sonos device is lan cabled. Do you have Playbars wifi module still turned on or did you manually turn it off?

Are there rearspeaker and / or a sub bonded with the Playbar? In this case the wifi module has to be turned on.

If it’s still activated the Playbar does create the SonosNet and your system will operate in a mixed mode using router wifi and also the SonosNet. So your interferences may come from your own network. 
Within Sonos app you can choose channel 1,6 or 11 for SonosNet. It’s on 2,4 GHz and all other SonosNet supporting devices will try to connect to it. Your routers 2,4 GHz wifi should be set fixed also to one of these three channels, but a different one than SonosNet uses. 
The other option would be to use router wifi exclusively and turn Playbars wifi module off. But that option only makes sense, if Playbar is used stand alone without sub / rearspeakers.

I’ll check the channels for conflict, but 90% of the time the playbar not even powered on since it’s a guest bedroom. But you’re right that could be an Interference issue. But when I had the problem the other day the playbar was not powered up.

The playbar is standalone for the TV in the guest bedroom. There is no sub Or rear speakers with the playbar. 

Ok… in that case I would try to deaktivate Playbars wifi module within Sonos app room / product settings. 
Maybe some devices are still searching for the SonosNet if the Playbar is cut from power. Switching from SonosNet to router wifi and vice versa can take up to 10 Minutes and cause problems. 

OK I’ll give it a try.

There was just a new update, I’ll see if that helps also.