Download Firmware 1.01 and 1.11 for Nikon's D5600 and D3400 Digital Cameras
Nikon Firmware Updates (28/02/2017) for D3400 (Ver.1.11) and D5600 (Ver.1.01) Cameras: Connections Between Cameras and the iOS 10.2 Version of the SnapBridge App – Photoxels
Nikon D3400 DSLR Camera | Interchangeable Lens DSLR Camera with SnapBridge Connectivity
How to Update the Firmware in Your Nikon Digital Camera | Nikon