Beneath are instructions for retrieving your router IP address on any iOS device.
Undo your iOS device
By tapping on home key navigate to home screen
Click on “Settings” app. normally it is at the end list of the apps however it even can be in other location in app list
Search for Wi-Fi & tap in Settings app on it
You must get list of available Wi-Fi networks. Active Wi-Fi network will be kept with checkbox.
Click on active Wi-Fi link
Search for line with “Router” in it. Your router IP address will be in this line