Can't login to access point (Netgear R6080)

I just installed a GL-AR300M as my home router with my Netgear R6080 as the wireless access point. However, I cannot login to the R6080 using the ip address assigned to it by the GL-AR300M. Any idea on how I can fix this?

Does R6080 works in bridge mode?

If not in bridge mode, what UI does it have?

Maybe it has firewall and blocks all the input data from WAN side (when you access it using the IP obtained from AR300M, you are accessing from WAN side).