How do I get a AC1750 (R6350) to work with a MR 1100?

[BillFromMD]

MODEM/ROUTER: Netgear MR 1100 cell hotspot
ROUTER: Netgear AC 1750 (R6350)

I am having ZERO luck setting up this router.

I've been through the setup process half a dozen times with the Netgear Nighthawk app and it's just not happening. I never get the Internet light to light up as any color, which leads me to believe this unit isn't detecting an Ethernet cable. I've tried two cables - one was the one provided and the other the one I use for my PS4, which I hard wire all the time with the MR 1100 with no issues so I know it's not faulty. I only get two lights lit - power and Wi-Fi. The other two lights have never come on.

I initially tried changing the hotspot modem/router to pass through its internet by enabling IP passthrough and disabling DHCP. The MR1100 recognized that the router was connected to it because it said 1 device detected. I never got the router to detect that even a ethernet cable was connected. I then did a factory resest on the MR1100 modem/router (since it was no longer prioviding Wi-Fi since I'd told it not to) and still no luck. 

I haven't been able to complete setup with the Nighthawk app and I've been unable to login to the router with routerlogin.com because it doesn't recognize an internet source.

I'm ready to just take back this modem and give up. Is there ANY hope for setting up this router with a MR 1100 modem/router? They're both Netgear. I didn't think it would be THIS difficult!

So, what should I do besides return it?

[BillFromMD]

Exchanged it, still having the same issue of not being able to login to the router and the router refusing to recognize the Ethernet cable and the incoming internet. I'm usually the same Ethernet cable I use every day to hardwire my PS4 from the MR1100. Yet Netgear's own equipment refuses to recognize it. The AC1750 is going back tomorrow and I'm getting my $95 back.