You only set a PPPoE connection on the router, all other devices you setup to use the local LAN/Ethernet or wireless connection that the router is providing. You wouldn't enable PPPoE on the Xbox or any other device. How are connecting the Xbox to the router? Wired or wireless? Dynamic address(DHCP)?
And what are you using the second router for? Having two routers connected to each other creates other issues and you may have to change or reconfigure your setup or that second router depending on what your intention is.
And what are you using the second router for? Having two routers connected to each other creates other issues and you may have to change or reconfigure your setup or that second router depending on what your intention is.