Newbie question about interfaces

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C#

architecture

I'm still pretty new to using interfaces and I'm unsure if I'm using interfaces as they are intended. What should I do if I have properties in my interfaces that won't be used by the implementing class? What if I have I functionality that is generic - should I rather be using a base class or be implementing multiple interfaces? I'm really just asking for someone to confirm whether or not I'm on the right track here, because I feel like I'm missing something simple.

An example below:

interface IPrinter
{
	string IPAddress { get; set; }
	
	void Print();
}

public class EthernetPrinter : IPrinter
{
	public string IPAddress { get; set; } // IPAddress
	public void Print() { Console.WriteLine("Printing over ethernet"); }
}

public class SerialPrinter : IPrinter
{
	public string IPAddress { get; set; } // Not going to be used. 
	public int CommPort { get; set; } // this is the actual property I need.
	public void Print() { Console.WriteLine("Printing serially"); }
}

And then use it like this. But aren't I supposed to be getting away from if statements with OO programming?

IPrinter printer;

if (someSetting == "UseEthernet")
    printer = new EthernetPrinter() { IPAddress = "1.1.1.1" };
else
    printer = new SerialPrinter() { CommPort = 1 };

printer.Print();

What I have tried:

But then I see that I could be extracting the interfaces a little bit further to use the connection for other devices, but this doesn't feel much better.

interface IDataSender
{
	void SendData();
}
interface ISerialDataSender : IDataSender
{
	int CommPort { get; set;}
}

interface IEthernetSender : IDataSender
{
	string IPAddress { get; set;}
}

interface IPrinter
{
	void Print();
}

public class EthernetPrinter : IPrinter, IEthernetSender
{
	// this looks good
	public string IPAddress { get; set; }
	public void Print() { Console.WriteLine("Printing over ethernet"); }
	
	// but this feels like this should be in some other class 
	//as this could be pretty generic to any ethernet device.
	public void SendData() 	{ }
}

public class SerialPrinter : IPrinter, ISerialDataSender
{
	// once again, this seems correct
	public int CommPort { get; set; }
	public void Print() { Console.WriteLine("Printing serially"); }

	// but this doesn't.
	public void SendData() {}

}