I just got the Sonos controller working with Windows 10 on my workstation - thanks to Carl at Sonos support! My workstation app used to work until a month or so ago. I verified my workstation is on the same network as my other devices that use Sonos. I verified my firewall settings are correct per the Sonos writeup about this issue. I finally decided to call support and Carl was kind enough to walk through every thing with me. According to Carl, Sonos updated their privacy policy in June. I did not know this.
Here's how I fixed my issue:
On the SONOS app on your phone, go to your account settings (top right corner, the person icon to the left of the settings gear icon). Under the Legal and Privacy heading select Privacy and Security. Scroll down to Connection Security. You should see 3 settings. 1. Authentication, 2. UPnP (Universal Plug n Play), 3. Guest Access.
According to Carl the default settings should be Authentication OFF, UPnP ON, Guest Access ON.
All of my settings were set to OFF. I had no idea about these settings or how they should be configured!
It turns out UPnP needs to be turned ON!
From Sonos website https://support.sonos.com/en-us/article/adjust-connection-security-settings
UPnP: This pertains to integrations that utilize the unsupported UPnP protocol. Note that turning this setting off will also prevent the Sonos app for macOS and Windows from controlling your system.
Once I turned on UPnP the Sonos app worked on my Windows 10 workstation.
I wish SONOS would have sent an email out about this update. I spent alot of time trying to figure this out. I should have called Sonos support sooner. Carl was very patient and helpful! Thank you Carl!