@BD45 Is your WAN IP address public or private ? If you haven't configured DMZ or Virtual Servers there shouldn't be any open ports on your device. Can you test while UPnP is disabled to scan again...

@RouterHang Yes, you could do that - here's an example for Deco ethernet backhaul. In this case you'll have a mesh network and seamless roaming.

@RouterHang That's correct. This is by TP-Link's design for OneMesh.

@ChaN-M0-Kei Check these answers: https://superuser.com/questions/887081/unknown-securenat-device-showing-up-inside-my-network...

@Dreammaster007 I would assume that you're connecting wirelessly to each device. if that's the case then this is probably due to a wireless interference between your devices, with neithbours wireless...

@Caffinite Archer C9 doesn't support DFS channels and that's the reason you don't see other channels than 36, 40, 44 and 48. I believe this is the latest FW version that you can use for your device,...