Unable to access web GUI, "routerlogin.net didn’t send any data" - AC2000/WAC124

[HandinBrand]

Whenever I attempt to view Netgear's web portal (through 192.168.0.100 or http://routerlogin.net) I get directed to the Netgear login landing page. Once I log in, I get a page with the following message:

This page isn’t working

routerlogin.net didn’t send any data.

ERR_EMPTY_RESPONSE

I did purchase this product used, but an initial support call got it registered under my account. The Wi-Fi and ethernet both work fine, and I am able to make changes through the Genie app, but I do not have access to "advanced" settings such as port forwarding without acces to the web GUI. I have tried many of the suggested solutions from this website to no avail. 

Thank you for your help.