@Mustafa320 Can you try to add the devices manually by entering their MAC addresses? If that still fails, please take a short video that shows the issue, then @Kevin_Z may suggest.

@Damiannn A factory reset on the Archer C9 should restore the connection. You can connect a computer to the C9 by cable directly to confirm if you have internet access. If yes, that means the C9...

lacrimal wrote See that Archer C6 is planned for Easy mesh but only v4 version. Will v2 version receive this firmware too or it will never happens ? @lacrimal You can keep an eye on the EasyMesh...

@JIFourie I see. You are right, you cannot choose channel 165 on an EU hardware. You can try to contact the shop to see if they are also selling the US versions.

@Zombielicious Thanks for sharing the solution. I suggest marking the solution as the recommended solution, then others may benefit from that.

@LordBeerus It seems there is a similar thread below, you can check my suggestions to skyfx64 and confirm if any helps: https://community.tp-link.com/en/home/forum/topic/590052