Hi. What other Sonos equipment is in your system and is anything else wired to your router?

Further question. When the Playbar works, does it work for music sources as well as TV sound?

A speculative possibility….

I wonder if the 5GHz radio has failed on the Playbar.  This would normally be the means by which the Playbar and Sub would communicate, using direct routing.  The 2.4GHz radio is clearly still working, as the Playbar remains connected when the Ethernet cable is removed.

So maybe it is able to find an alternative route round the network to connect to the Sub when wired, but not when wireless.  Possibly because the Ethernet cable “frees” the 2.4GHz channel for that connection.  HOWEVER, I don’t even know if the Playbar has separate radios for 2.4GHz and 5GHz, so that one but not the other could fail.  I’m not totally sure that anything I have written makes technical sense!

You could run system diagnostics with and without the cable, and contact Sonos Support with the confirmation numbers.  

Thanks John for the fast reply.

1. There is no other Sonos equipment

2. It does work from TV and Apple Music in my case
3. I don't know the internals of the Playbar either but don't you think it is unlikely that a hardware failure causes the issue when it happened almost immediately after the update (like two or three days after) when working perfectly for at least 2 years.

In my experience when there hasn’t been an update people say ‘my Sonos has gone wrong’.  When there has been an update, everybody blames the update, which is almost never the culprit.  When there has been a genuine problem with an update (very rare) the forum drowns in posts about it.  If something this fundamental had occurred from the update, everybody would know about it.

I think it is about a million times more likely to be a hardware fault or other local issue than a bug in the update.