2 Nighthawk R7000 on same network

Dear friends,

    The problem: With two Nighthawk R7000s on the same LAN, I can only log in to one of them but not the other. My goal is the make the wifi SSIDs of the two routers be the same.

    Background: I have two R7000s on my home network. The main one hangs directly off the cable modem and feeds the ethernet ports I recently had wired up around the house. The auxiliary one connects to one of those ethernet-out ports via its WAN-in port and acts as a switch for other ethernet devices close by as well as a secondary WiFi AP to extend the range of my wireless network. During setup for the auxiliary router, it detected the main router and I chose to place it in wifi AP mode, but currently, the SSIDs of the two routers are different, which is why I'm trying to log in to the auxiliary router.

    Symptoms: I can log into the admin interface of the main router via 192.168.1.1 or routerlogin.net. However, I cannot log in to the second router's admin interface. I use the main router's interface to determine the IP address of the auxiliary router. However, when connecting to "192.168.1.15", I see my address bar show "http://192.168.1.15/start" and then very quickly redirects to "https://www.netgear.com/home/services/routerlogincom/" which shows this error: "You may not be connected to your Router’s WiFi network. To access routerlogin.com, your device must be connected to your Router’s WiFi network. Check your current connection and try again."

    Trials: I've tried these scenarios, where 192.168.1.1 is the main router's IP and 192.168.1.15 is the auxiliary router's IP:

Scenario Ethernet WiFi IP Result

    I've gone through all the combinations I can think of, with no good results. Any ideas? Thank you for your help!