Try unplugging it, then reboot your router, once the router comes back up, plug it back in. Also, check for wifi interference between the SUB and whichever speaker it is bonded to,

In addition to Airgetlam’s post, try plugging it into another wall outlet and try swapping out power cables from one of your other Sonos products if possible.

How to swap the power cable, i try to remove the cable of the SUB but is too hard

I try to swap with my playbar and it still not work

Understood, if it still won't power up, how about we move this conversation to DM so I can grab some information to move forward with the return and replacement process.

same problem here. Sub makes no sound despite white light being on  

This is my diagnostics number 323895167

@adkarabay ,

Thanks for posting the confirmation number. I see the Sub is getting an Ethernet connection. Would mind telling me what device is the Sub plugged into via Ethernet and please provide the model number if possible.

Thanks,

hi Sebastien,

The sub was connected to Ethernet as I was trying to troubleshoot. It didn’t work it was connected to my WiFi repeater.  
 

I’ve reset the sub to set it up the initial way, still doesn’t work. I have submitted a new diagnostics report: 911591700

this was the setup I used for the last two years. The sub seems to be connected but just simply doesn’t work anymore or frequently disappears. 
 

When you mentioned WiFi repeater, are you referring to a wireless extender or an access point? If so, turn off that device temporarily and try the setup process once more.

Please provide the following information to have a better understanding on how your Sonos setup works, there are many reasons that could explain the issue you are experiencing and this will help to pinpoint the cause:

1. The make and model of the Router you are using.

2. Please list the controllers you have attempted to connect to the Sonos system (iPhone, iPad, Android device, PC or Mac).

3. Do you have any additional networking devices? This could include wireless network extenders, network switches and power line adapters (not other Laptops, Gaming Consoles, NAS drives). If so please provide the make and model numbers (usually found on the device). 

I have the same problem.

The sub was working fine.

One day it just stopped working. There is no more light. The sonos application can’t find it.

I already tried to use reconnect procedure, come back to manufacturer configuration and used different wall outlet, reconnect the power cord.

And I am in Brazil. I bought it less then two years ago in Monterey California while I was studying. It was working well in Brazil and in US.

I am very disappointed, because I can’t  buy a new one here and I can’t use another sub in this system from a different brand. I feel like loosing the whole system.

I loved the sub, the sound was impressive!