First thing...Posting the reference number for the Daignostics is spot-on. However, you need to call Sonos Tech support to discuss the results.

Second...does the app show the sub as part of the setup for the room with the Beam? Pleas provide a screen shot of the room in the app showing the Beam and sub.

So the sub on the app appears within the room for a bit and then it disappears, I have the same setup In another room and I’m always able to see the sub with the option to remove it. If I select connect a sub I get a message with instructions on how to connect a second one. 

So I’ve checked the the sub is WiFi enable as well as the beam. I’ve defaulted them and reset the entire network let it come back up and then added devices back to the network. This setup has worked for a while until the latest Sonos update 

In order to connect a sub to your Beam you must first add the sub as a product by selecting “Add a Product”. Once the sub is added it may ask you where you would like use the sub or you may have to go the room with the Beam and select add a sub. 

That’s exactly how I’ve been adding the device. But have had no luck I’ve tried hardwiring but as far as I know they have to connect wirelessly. 

Hardwiring the device made no difference on the beam or the sub 

Typically the sub and any Sonos soundbar connects wirelessly. However you can wire the sub via Ethernet to get it into your system. However if the sub is appearing and then disappearing in the room then it may have a failing network card. Suggest you be contact Sonos tech support since you have already run the diagnostic.

Is there an easier way to contact them or possibly setup A call. Their waits times are super long at the moment. 

I feel your pain…but unfortunately not. I always try at the opening bell and have good success even during this trying time.

Thanks for all your help! I’m going to try to call first thing.