Hi @bex238, thank you for reaching out to us and welcome to the Sonos community. I’d be happy to help you all here and it would be best for those having trouble submitting a diagnostic report of your system for better understanding and see what would be best for the setup. Reply to us with the confirmation number. We and the community are always here to help.

@Rowena B. I just submitted a diagnostic report. The confirmation number is 667324451

Hi @bex238, thank you for your response and for submitting the diagnostic. Let me help you with this.

Based on the diagnostic, the Sonos Sub is online and connected to your Sonos Arc. There's interference in your network that may be caused by wireless congestion, and the Arc was detected as a dropped room. This could be the reason why the Sub is dropping off since the Arc is the one sending the signal.

Let me suggest the next troubleshooting steps if this will work for you and to isolate the issue.

• Remove Sub
  1. Open the Sonos app for iOS or Android.
  2. From the Settings tab, tap System.
  3. Under Products, tap the room you would like to remove the Sub from.
  4. Tap Remove Sub.
• Add Sub to another Sonos speaker
  1. Choose Room for Sub: Removes the Sub from the current room and adds it to a different room of your choice.

If you still encounter the same issue, the next step is to perform the factory reset your Sub and re-add back to your existing system. Observe the performance of your Sub. 

Let us know how you get on with the advice above and if the Sub will continue to drop off the system, I recommend contacting our Sonos Customer Care support to perform in-depth troubleshooting. Our phone support has the tools to check what's going on in your system and to remotely access your device to provide the best option for you.

Please feel free to reach out in the future if you have any other questions. You're always welcome here.