And without that I can't comment if the cable box has settings to change.
HOWEVER when I install the router I power down the router, move the Ethernet cable to the WAN port of the router then power up the cable modem, wait for lights to go stable then power up the router so I can configure the router.
Your post didn't reveal much.
I have a pretty standard Comcast cable box with my TV and two consoles in the living room. In the next room I have a modem and router connected to it for WiFi. I tried disconnecting the router from the modem and connecting it via Ethernet cable to the cable box, but had no luck with WiFi. My goal is to have the router in the same room as the TV and consoles.
Is there a way to connect the router to the cable box?