The Computer Browser service relies on the SMBv1 protocol to populate the Windows Explorer Network node (also known as "Network Neighborhood"). This legacy protocol is long deprecated, doesn't route, and has limited security. Because the service cannot function without SMBv1, it is removed at the same time.
However, if you still have to use the Explorer Network in home and small business workgroup environments to locate Windows-based computers, you can follow these steps on your Windows-based computers that no longer use SMBv1:
Start the "Function Discovery Provider Host" and "Function Discovery Resource Publication" services, and then set them to Automatic (Delayed Start).
When you open Explorer Network, enable network discovery when you are prompted.
All Windows devices within that subnet that have these settings will now appear in Network for browsing. This uses the WS-DISCOVERY protocol. Contact your other vendors and manufacturers if their devices still don't appear in this browse list after the Windows devices appear. It is possible they have this protocol disabled or that they support only SMBv1.
We've already established that Brennan devices support later versions of SMB (by mapping then to a drive letter with SMB 1 disabled), so this workaround should let you browse for your Brennan without enabling SMB v1 on your Windows computer. What your Sonos needs when talking to the Brennan is completely independent of what your PC does. Your Sonos should work even if you don't have a PC.