Can't acess Orbi RBK852 when configured as an AP

Reply was a bit long, sigh...

I took another run at this today.  First I restored factory settings and brought Orbi up in AP mode with a fixed IP.  Orbi came up, wifi OK, Internet access OK, but unable to access orbi admin.  I tried the IP address I configured it with, 192.168.1.1, and orbilogin.com.  I tried from orbi enet port and from wifi.  No go.

Then I restored factory settings again to get control over orbi admin and brought orbi up in AP mode using the preferred DHCP mechanism.  Orbi wifi came up, but no internet access.  I tried to logon using 192.168.1.1, orbilogin.com, and all 3 (yes, there were three at this point) IP addresses my wired EdgeRouter had allocated for Orbi (some reservations might have been from yesterday).  No go.

Then I tried this Windows trick over wifi:

netsh wlan show networks mode=bssid

arp -a

With my old Netgear R700 running in AP mode, I can easily match up MAC addresses returned by netsh command with IP addresses returned by arp.  But with Orbi, arp failed to register even a single match.

I'm thinking I'm going to return this, but I'm not very confident that another unit will behave differently.

One more call for advice.  Thanks in advance.

Comcast 1G/50M -> CM1150V -> EdgeRouter Lite -> RBK852

PS - posting keeps complaining that it finds "invalid HTML" in my message body, but second attempt seems to go through.