RBR850 Can't get internet from Xfinity xFi Gateway

So this seems weird to me. Looking at the RBR850 admin page, can someone help me decipher this?

ModestMBA is the laptop I'm using. The other device (C4:50:9C:42:A6:B6) is my modem. Is it normal that the router would be assigning an IP address (192.168.1.3) to the modem? That isn't what I would expect and seems to be indicating that it doesn't realize the modem is a modem or something?

Then in the image below, there's no activity showing but there IS activity showing on LAN1. The only ethernet cable connected to the router is on the yellow LAN port (visually double-checked). Wouldn't I expect to see activity showing here on the WAN port and not on the LAN1? Taken together with the IP address thing above, it almost seems like the RBR850 thinks the modem is actually connected to LAN1 instead of WAN, and therefore doesn't know it's a modem and is instead trying to assign an IP to it like a regular connected device. But I'm not sure if that's just me not understanding how this typically works?