@Natducati This is possible.  There are various ways to achieve that, depending on your expectations and the configuration of your house.
 

Do you have an ISP modem?

In all cases:

- the main Deco must be connected by Ethernet cable to a device giving access to Internet

- the Deco mesh will broadcast its own wifi, it will not extend the wifi of the Archer router

  @yves_b Thankyou for the reply.

What you describe is what I have ended  up with. The main deco is now connected to a ethernet cable and the satelilgihts are connected to the main Deco.

I do have an ISP modem.

I decided to use the Archer as thought this would give me greater speed .

Thanks

  @yves_b Hi, sorry for digging through this own topic here. I came across your comment and would like to ask you something. If I have the Archer set up as main router, from there connect to Deco nodes (put Deco in AP mode). If I manually set the wifi channel on the Archer, do you think if that settings will also reflect on those Deco in AP mode? I'm trying to set manual 2.4Ghz channel for my Deco cause it keeps overlapping with my Zigbee channel :(. Thanks

  @Espress0-0 Whatever its mode of operation (router or AP), the Deco mesh will independently decide which wifi channels to use.

In AP mode, the Deco will not act as a router (DHCP, NAT, ...), but it will not act as a wifi extender.  The wifi (and mesh) features of the Deco are not affected by its mode of operation.

What you want is for the Archer and the Deco to make a single mesh.  This is not possible today.  TP Link is apparently working on making their future products compatible with EasyMesh.  EasyMesh allows building one mesh with heterogeneous products, if they are al compatible with EasyMesh.

  @yves_b Thank you for the information. I actually chatted with TP-Link's customer service agent yesterday, and they told me that Deco would accept channel settings from the main router (even from non TP-Link routers). However, that doesn't seem accurate. Your explanation makes sense. What I’m suggesting is for TP-Link to allow advanced users to manually change channels. If they don’t want regular users to enable that option, they could keep it as a beta/experimental feature with a popup warning that it’s not recommended. This is frustrating because I like the extended coverage range of the Deco mesh, but I might have to switch to another system due to this limitation.

Edited: I just saw this post about Wifi 7 Deco supports channel selection (https://community.tp-link.com/us/home/forum/topic/717026). If I buy one pack of this, add to my existing Deco mesh and choose it as main router. When I select channel for this setup, will other X55 pro picks up what I set on the BE63 for example? Thanks again

  @Espress0-0 I would expect that the channel is always selected for the whole mesh by the main Deco, hence if you have the possibility to manually select the channel on the main Deco, it would apply to the whole mesh.

This is just an assumption, I did not read anything about that.