I have the same issue windows 11 on msi laptop
Tried delete all data in /user/appdata/local/roonserver & roon & raat
Reinstall and same server not responding
anti-virus Off
Firewall Off
If using Roon Lagacy 1.8 with old version of server it will work fine
7 months later it still issue 
After trying to update to latest roon version it’s same issue