Guide to determining NAT Type (Wii U/3DS): Type A: 11X-00 Type B: 12X-00 Type C: 22X-00 Type D: 22X-01 Type F: 000-99 When playing games like Splatoon or Mario Kart 7, you'll ideally want types A or B. Ask your ISP if you can upgrade from C, D, or F as necessary!