I'm a long time owner of Playbar and two play one speakers. They have been a very good surround system. I finally decided to complete the system with a base sub. Wanting the best hardware I bought the newest version, the sub 4.
I set it up with the app and found out it was not compatible with my old hardware.
All these products are connected via Wi-Fi and Sonos has decided that they don't want us to use the sub 4 with my old hardware. I'm sure this is a way to get us to buy new hardware where it is not needed. Backward compatibility is a good business model for the uses. They have decided they don't care about that, they want more money.
DON'T BUY SONOS.
Yes, I contacted tech support, their answer is send the sub 4 back and get the older sub.