Reflash DLink AC1750 Optimum Router

Question

I recently got the new "smart router" from Optimum: DLink AC1750

It may be a good router but I cannot access any of the settings. When typing in the regular 192.168.1.1, it redirects to https://router.optimum.net/basicSettings.html

So the two issue with that is that a lot of the configuration features that this router offers in inaccessible. Also, I would rather not have the router accessible via the web.

Is there any way to reflash the firmware or disable to Cablevisions default easy setup redirect?

Thanks!