Aimesh allows your main router and the secondary router (strictly in access point mode) to be connected over wireless instead of ethernet.
Modem -> Main Router port -> Node WAN port
The above link can work (because the node will convert the WAN into another LAN port.)
The below won't work because the node router cannot operate while connected directly to the modem, it need a main router to do the routing operations.
Modem -> Main Router WAN
Modem -> Node WAN