Hi @GRB2023
Welcome to the Sonos Community!
Your Sonos Music Library not being found after changing the network name of your PC is completely expected - the network name is how your Sonos speaker finds your PC. Please remove all entries in your Music Library settings and add the music folder once more (after you’re able to connect to your Sonos system in the app - see below).
As for the app not connecting, that’s via a different connection route and not so expected after the name change. I would first make sure that Windows thinks your network is a Private one, as opposed to Public.
To change a Wi-Fi network to public or private
- Select Start , then type settings.
- On the Wi-Fi settings screen, select Manage known networks, and select the network you're connected to.
- On the Wi-Fi network screen, under Network profile type, select Public (Recommended) or Private.
To change your network from public to private using the Ethernet Lan settings:
- Open Settings from the Start menu.
- From here, select the Network & Internet settings option.
- Select Ethernet from the menu on the left.
- Click on the name of your connection.
- Select Private.
Please also make sure that any firewall software installed has exceptions for sonos.exe and sonoslibraryservice.exe (both found in C:\Program Files (x86)\Sonos).
I hope this helps.