Follow this guide for setting up the Archer AX1500(AP) - Case 1. Ensure you are using Internet port of AP(AX1500) to connect the wire to the Archer AX10 LAN port. When setting up the LAN IP address...

In my opinion you should use AP mode via WAN port with DHCP server in auto or off mode on the AX20. I would prefer DHCP server to be off since your primary router has DHCP server enabled already. You...

That leads us to the initial issue again - there's no internet access to the Archer C6 device itself (although its clients have an internet access). I can see that you are not getting any IP address...

@loll80 Is your Archer C6 US or EU version ? If it's EU version then the latest one should be here. if that's the case upgrade to that one (v1.3.6) and see if that helps. The final option I can think...

Try this link for v1.2.1 or this link for v1.0.1.

Yes, this is the way it should be configured. The video guide for Archer C6 you followed is for so called "manual access point mode" probably. If you configure the router through the Operation mode...