@romilly 

In a network, you want only one device set in router mode.

For example, if you have a gateway (modem/router combo) and you want to connect a router to it, you would put the gateway into bridge mode and attach the router to it. The router would then would control the eithernet and WIFI.

Another example is to to have the gateway or your main router be the main control of the Ethernet and WIFI and add aother router in AP (Access Point) mode.

You do not want two routers in 'router' mode.

Put the TP Link router in AP mode.