Replace Logitech Squeezebox Duet

What url for the browser? I can open the server app on the pc but have not seen an option for a list of players.

Virtually any streamer. Load piCore player (free) onto a RasPi ($100 on up)
Gives you full blown LMS with UPnP. It should see your PC.
If you put your music on a local drive you can see it and load it via WiFi anywhere on the network with your PC. Probably can on iOS too but I would not know or care how.
Make sure you put it on a surge protector.

something like:

http://192.167.1.237:9000/

ip address of computer running the Logitech Media server and port 9000


Players connected to the server should show in dropdown menu in the upper right.  If not try restarting Logitech Media Server and if still not there rebooting the Squeezebox.

The drop down shows no players. The Duet box is connected by Ethernet.  The remote gives me an option for wireless or Ethernet. I choose Ethernet and it never finishes looking. If I select Wireless it finally gives up saying it can’t find my network. Even though an earlier setting showed my network pre-selected.

BTW, I've got a SQ touch and I've switched to using Roon instead of LMS and I am so happy. 

The screen integration is not great, but Roon is a dream to configure install vs. LMS.