I've no idea why the IP went weird - I could ping it too which is what threw me completely as it seemed fine. I went back to the beginning and used a different IP out of sheer desperation. I was trying to sort of disassociate the printer from all previous arrangements to rule out any unseen issues, and for me, it worked (for now anyway)
I would definitely do all the other stuff mac_shinobi suggests as well.
Good luck! Let us know how it goes