Several potentials here, not sure which applies, as there’s not enough information in your post.
What Sonos speaker is your SUB bonded to?
Have you turned off Wi-Fi on any of your Sonos speakers?
When you look in the controller, under Settings>System, what does the room name look like for the room that has the SUB in it? It should be a room name, followed by parentheses. We’d be specifically interested in what shows up in the parentheses.
Sorry, so the set up is as follows
Beam connected to router ethernet
Two Sonos ones connected via WiFi as surround setup
Sub connected via WiFi
All assigned to one room set up. So in app shows +Sub+LS+RS bounded to beam
Boost which is also connected via ethernet.
Two Sonos ones in separate room set ups connected via WiFi.
If I remove the WiFi from the beam will that kill the connection with the two surrounds?
The SUB is connected to the Beam?
Yes, if you remove the wifi from the Beam, that will stop it from being able to connect to both the SUB and the surrounds. The ‘bonded’ speakers use a separate wifi signal than your 2.4Ghz channel to talk to each other, turning off the radio turns off that system.
So, with the room name being correct, we know that your router is aware of the SUB being connected through the Beam, that’s great. The next question becomes one of the signal, rather than the connection. Turn on the TV, and play a movie where you’d expect the SUB to be working. Open up the controller and go to Settings>System>About my System. Look for the area that describes the Beam, and tell us what the line that starts with “Line In:” says. I’m willing to bet that it currently says stereo, but would love to get confirmation of that.
Also, what are you feeding the TV with? Are you watching a local channel on the TV’s tuner, or are you using some sort of cable box, game console, etc?
As an aside, you don’t have to have both the Beam and the BOOST connected, just one will do, but that’s not going to have any impact on this issue, unless you’ve got one sitting on top of the other, creating interference.
Which is also a good point to bring up. Since the SUB is connecting to the Beam on its own 5Ghz network, you need to be sure there’s nothing near the Beam, or the SUB, that could be interfering with that kind of signal. I’d think if there was something near the Beam, you’d be having issues with the surrounds, so I’d be looking in the vicinity of the SUB, and even try moving it to a different location/plug in the room to be certain.