Sounds more like some sort of wifi interference , related to something that occurs on Sundays. You may want to submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.
There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.
When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your Sonos system and network.
I certainly am not experiencing the need to reboot my system every week.