Failure to recognize a NAS on my LAN

Dear Readers -

I'm having trouble getting my network attached storage recognized and communicating properly within my LAN.  My NAS worked fine with my previous service provider's gateway, but I'm having no luck with my new Xfinity gateway.

When I connect the NAS (via hardwire ethernet) to the gateway and power it up, my Xfinity phone app announces "New device connected:  A new Western Digital MyBook Live connected to your home network."  But, when I view the device details on the app, it tells me there is no IP address assigned to the NAS.  So the NAS is connected, but I can't communicate with it via an IP address.  Also, the NAS is not discoverable from any of my PCs on the LAN by Western Digital's device setup software.

Details follow:

• My gateway is Xfinity's xFi Advanced Gateway (XB7, Part no. CGM4331COM, rented from Xfinity).
• My NAS is a Western Digital MyBookLive with a Linux OS (Part no. WDBACG0020HCH-00).
• The NAS is hardwired to the gateway via ethernet cable to the gateway's port no. 1. 
• Connection via ethernet cable is the only available option;  there is no USB support.
• When I look at my LAN ethernet port status (via the gateway admin portal, http://10.0.0.1/lan.jst), I see that ethernet port no.1 (of 4) is indeed active.
• For now, I am trying a DHCP connection, though eventually I would like to assign a reserved local IP address.

I wondered if a security or a firewall issue was preventing communication.  So I did the following:

• Using the Xfinity phone app, I disabled the Xfi Advanced Security feature. 
• I disabled the IPv4 and IPv6 firewalls via the gateway admin portal (see http://10.0.0.1/firewall_settings_ipv4.jst and http://10.0.0.1/firewall_settings_ipv6.jst).
• On the gateway admin portal, under "device discovery," (see http://10.0.0.1/device_discovery.jst):
  • I ensured that UPnP was enabled (it was).
  • I enabled zero config (a discovery protocol that allows UPnP-capable devices to connect automatically).

The result was the same.  The NAS is apparently connected, but no IP address is assigned to it.

Any advice would be appreciated.