PaulS:
You can use the W5500. Whether it works with the "old library" or not depends on what the "old library" expects the ethernet shield to do.Specifically, which "old library" are you talking about?
Thanks for the answer!
Well, i found this: https://github.com/arduino-org/Arduino/tree/master/libraries/Ethernet2 which adds new features. I just assumed the classic Ethernet library was "old" by now. My bad I'd say. I'm of course talking about the Ethernet library included with Arduino once it's installed!
I'll try the shield then, hope I won't burn anything haha