How to use reflection on nested classes in order to get values

I have to an upper class with nested classes

public class Preferences
{
	public FunctionClass function { get; set; } = new FunctionClass();
	public class FunctionClass
	{
		public string programfolder { get; set; } = "";
		...
	}

	public LoggerClass logger { get; set; } = new LoggerClass();
	public class LoggerClass 
	{
		public string logFolder { get; set; } = "Log";
		...
	}

	public OptionClass options { get; set; } = new OptionClass();
	public class OptionClass
	{
		public bool showGraphics { get; set; } = true;
		...
	}

	public MqttSpSetupClass MqttSpSetup { get; set; } = new MqttSpSetupClass();
	public class MqttSpSetupClass
	{
		public string strAddress { get; set; } = "localhost";
		...
	}
}

so I want reflection to cycle on all member of each inner class

PropertyInfo[] props_Outer = typeof(IoAppPreferences).GetProperties();
int counter = 0;
foreach (PropertyInfo prop_Upper in props_Outer)
{
	var sName_Outer = prop_Upper.Name;
	var val_Outer = props_Outer.GetValue(counter ++);
		
	PropertyInfo[] properties_Inner;
	switch (sName_Outer.ToUpper())
	{
		case "DIMS": properties_Inner = typeof(IoAppPreferences.DimsClass).GetProperties(); break;
	 ...	
	}

			 
	foreach (PropertyInfo prop_Inner in properties_Inner)
	{
		var sName = prop_Inner.Name;
		//prefs.function

		var sVal = prop_Inner.GetValue(val_Outer);<------ERROR

		switch (prop_Inner.Name.ToUpper())
		{
		 ...			
		}
	}

I get an error where I put the arrow. And the reason is that val_Outer is FunctionClass function while if I hardcode prefs.function it is ok. Of course, I can put a switch per each one, but my question is: is there a better way to solve it?

I have seen this solution but can't fit to my needs

You got error because val_Outer is wrong instance. You are trying to get value out of counter integer props_Outer.GetValue(counter ++)

If your goal is to get property values from nested classes you must have instance of Preferences object:

    var appPreferences = new Preferences();
    var propsOuter = appPreferences.GetType().GetProperties();

    foreach (var po in propsOuter)
    {
        var valueOuter = po.GetValue(appPreferences);
        Console.WriteLine($"{po.Name}");

        if (valueOuter == null) continue;

        var propsInner = valueOuter.GetType().GetProperties();
        foreach (var pi in propsInner)
        {
            var valueInner = pi.GetValue(valueOuter);
            Console.WriteLine($"{pi.Name}: {valueInner}");
        }
    }

But getting values through reflection is pretty much useless if you already have object instance.