Help with WAN Aggregation Setup - CM1100 and RAX120

Hello,

Just recently got a new RAX120 and trying to get it setup with my CM1100 modem.

Everything is working so far, was able to get the router setup, internet is working, Wifi is good, but can't seem to get WAN aggregation working.

- Router is updated to latest firmware

- Have LAN 1 Port on CM1100 going to WAN/INTERNET port on RAX120

- Have LAN 2 Port on CM1100 going to LAN 1 on RAX120

- Have gone into setup and chosen "WAN aggregation"

- Whenever I hit apply and it goes to make the changes it comes back with: "Error: Unable to establish WAN aggregation."

- Both port lights are lit on my CM1100 and there's no loop process happening or anything / both are lit solid as if functioning normally, not flashing or anything

Really not sure what I'm doing wrong. Have read through many other threads and followed the same process yet I can't seem to get it to work even when repeating the steps others have tried.

Any help would be greatly appreciated!

Thanks!