Cannot access R8000 controls after firmware upgrade

Upgraded to Firmware V1.0.3.26_1.1.18.  Ever since the upgrade, I cannot get into the router settings.  Netgear Genie on an Windows 10 machine (connnected via ethernet cable) lets me get to the "home screen" but if I try to log in I get a message "NETGEAR router is not found or is not supported.  Also make sure the device is not connected to the guest network of the router and no IPv6 in enabled."  I get the same message on a Window 7 machine connected via wifi (not the guest).  (All I can see is the network map & internet traffic before it asks me to log in, then I get this message when the login screen loads.)

Tried the http://routerlogin.net, http://192.168.1.1, and http://192.168.0.1 on both windows 10 (Edge and Chrome) and windows 7 (explorer and chrome).  All 4 browser versions say the site cannot be reached.

Also tried netgear genie on 2 different android devices, both had worked previously.  When I try to log in, the "please wait" spinner just goes around and around.  (update, after 5 minutes+, the same message above comes up on android device)

I've power cycled the router.  I have not done a factory reset.  If I do and it won't let me in, it's game over.  Any suggestions?!