GetMyIPAddress.cs

string GetMyIPAddress()
{
  var icp = NetworkInformation.GetInternetConnectionProfile();
  if(icp == null)
    return string.Empty;

  var adapter = icp.NetworkAdapter;
  if(adapter == null)
    return string.Empty;

  var hostname = NetworkInformation.GetHostNames().FirstOrDefault(
  hn => hn.IPInformation?.NetworkAdapter != null
     && hn.Type == HostnameType.Ipv4
     && hn.IPInformation.NetworkAdapter.NetworkAdapterId == icp.NetworkAdapter.NetworkAdapterId
  );

  return hostname.CanonicalName;
}