Cannot login to Netgear modem/router C7000v2

I have a Netgear C7000v2 cable modem/router. Been using it for years and it's still working. However I can't log into the router either through the Nighthawk App on iPhone, nor through 192.168.0.1, nor through routerlogin.com / net.

Nighthawk returns with 'We can't find your router'.

Using 192.168.0.1 via Chrome and Safari returns with 'This site can't be reached. 192.168.0.1 took too long to respond'.

Routerlogin, also via Chrome and Safari returns with a site to tell me to use Nighthawk.

I used to be able to get my router's login page where I enter my usernamd and password.

I've tried most suggestions I see posted in the community but am still spinning my wheels.

Any help is greatly appreciated.