I bought a pair of TL-WPA9020P Kit and have been using them to give internet connection in my room. One unit is connected to my modem in the living room on a wall socket, and the 2nd, paired unit is plugged onto the wall in my room.

For 6 months, I have set up a TOTO LINK N300RH router which is quite old, to plug into the 9020P in the room, so that I can get wifi. I recently bought a TP Link Archer C60, thinking it would give better speed with dual band, but after I connected it to the 9020P and set it up, the C60 fails to set up an Internet connection.

Since the 9020P has 2 eternet outs, I removed the C60, plug a notebook pc directly to the eternet port,  but the notebook pc screen says "unidentified network" with no connection. All 3 lights on the 9020P are on solid green, and when I plug back the old TOTO Link N300RH, I get Internet connection again.

I can confirm that the C60 router is not faulty as I plugged it directly to my modem in the living room and it gives me Wifi and Internet. But when I wire an eternet cable to the 9020P and then reconnect it to the paired 2nd unit in my room, the same problem persists--it fails to set up an Internet connection.

Is there some trick that the 9020P somehow only recognizes my old TOTO Link router but not the other devices, and hence blocking my signals?