I have the same problem with one of my two Amps. On one, I chose to disable wifi, and it worked. On the other, no matter what I do it just spins quick on the screen that says disabling wifi but then returns to the device screen after like ½ a second, still connected to wifi. Tried swapping the ethernet cables. No joy. Grrr.

To those who are struggling because of the latest update to the Sonos app, I have found a way to disable the Wi-Fi. I can’t believe this actually works, but if you disable Wi-Fi, let it finish, then immediately power off the Sonos amp when it finishes. Then when it powers back on the Wi-Fi will stay disabled!! I have 10+ sonos amps on a unifi network so naturally to avoid STP issues i need to have them all on ethernet only. In the past this was easy but ever since the latest update disabling Wi-Fi stopped working. But with this trick, you can actually disable the Wi-Fi until Sonos pushes an update to fix this issue. Hope this helps someone who is struggling.

latest app update today - no error when disabling wifi, it just doesn’t work lol

click to disable, it says its disabled. then the arc reboots on its own and its enabled again. sonos engineers are absolute clowns.

I’ve had the same issues. Trying to disable wifi on a Beam, Amp has been near impossible….

2 questions, have you tested this also with other devices (I have the arc) and when do you see, when it finishes? 

Nope thankfully I already had the arc WiFi disabled. I only tested this on the new amps that I purchased. Basically you go into the app and disable the WiFi, then right when it finishes pull the power cord to the amp, then when it reboots it will actually keep the WiFi disabled. If you get an error message when disabling the WiFi you might just need to reboot the amp and try again. The secret sauce is simply unplugging the unit right after the app shows that you successfully disabled the WiFi. I know it sounds crazy, but I just setup 5 new amps using this bizarre method. Alternatively if you have an old version of the app some people had success with that too but unfortunately i don’t. I’m using the iOS app. 

Just tested this on my Arc - it worked. I clicked disable in the app and as soon as the app finished the screen and blinking stopped on my arc, I pulled the plug. Plugged it back in. Wifi stays disabled. 

Haha that’s great!! I hope Sonos engineering is reading this thread

A sometimes significant detail:

The vocabulary associated with WiFi ON/OFF is unfortunate. ‘Radio’ ON/OFF would be a better choice. Wireless subwoofers and surrounds use a private 5GHz link to the soundbar. If the soundbar’s radio is disabled, wireless SUB’s and surrounds cannot work.

False. 
 

you can have everything connected via Ethernet with all WiFi off. Sonos communicates in HT and paired setups over Ethernet exclusively. No WiFi, no Sonosnet, etc. 

ethernet is the best way to use Sonos provided you have WiFi turned off to avoid any spanning tree issues. 

I have a Sonos system at home with 3 rooms, one of them has 2 fives in stereo and one sub, I decided to connect the three of them using Ethernet, I went to the app, selected a Five, clicked Disable WiFi and my ENTIRE system in the house disappeared from the app and made the speakers a very expensive door holder. I’m unable to add them back to the system even after factory resetting them. 
 

I’m done with WiFi audio and with Sonos in particular. I went with Ethernet because I was experiencing disconnects all the time (even when speakers were close to the WiFi)

I literally made 3 EXPENSIVE speakers unusable by connecting to them an Ethernet cable and clicking “disable WiFi” 

Thanks for this, I was struggling with this for the last month. Error after error. I am running a unifi system and just wired up my external garage with a 200ft fibre cable.

This left the sonos trying to connect on sonosnet or whatever and also triggering the STP on the switch.

I ended up sitting beside the amp, flipping the WIFI to disabled and after a bit while it was blinking white I pulled the plug and let it die from power loss. Plugged it back in and it stayed disabled.

I then had to do this same thing to my PORT and to my SUB.

A GIANT PITA. Thanks for the direction!