Ethernet-Connected Printer Not Showing as Connected Device

A non-WiFi printer connected to the Ethernet port of an XB8 gateway does not show up as a connected device either in the Xfinity mobile app or in the list of Connected Devices using the Admin tool website. However, the printer is recognized and prints using a computer on the network and its IP4 address and MAC address show when doing an "arp -an" command.

Multiple restarts of the gateway and printer did not resolve this issue. Where can I find the printer and its assigned IP address from the Xfinity app or the Admin tool?