@ET13 Of course you can use ER650 as your main router and C80 in router mode in Easymesh, The thing is that in this scenario you'll create a double NAT in your local network. If that's not an issue...

@Matt_V When the AX23 is configured in AP mode its DHCP server should be disabled (turned off). In this scenario your main router should be the DHCP server - Here's a guide on how to configure AX23...

@Mohammed_A_Ali No, you can't. Deco mesh (M5) is not compatible with Easymesh (AX55 pro) - details.

@siens TP-Link uses self-signed certificates - ther's nothing to download. If you already configured HTTPS access, use this guide for accessing the router's WebGUI. If you want to enable WebGUI HTTPS...

@Matt_V Remove the ethernet cable from AX23 LAN1 port and plug it into the WAN port (blue port). Then everything should be fine.

@Veryyconfused Make sure that you're with the latest firmware version on your WA850RE - from here. If not, download it and update manually - here's how.