Ensure your phone or computer is connected to the router via Wi-Fi or an Ethernet cable.
If you have tried all default combinations and still cannot log in, the password was likely changed during the initial setup. You will need to perform a :
The lights will flash, and the router will reboot. All settings will return to factory defaults, allowing you to use the original credentials printed on the sticker.
Many modern H196A units come with a unique password printed on the label at the bottom or back of the device.
Locate the small "Reset" hole on the back or side of the router.