Any good reason not to try this

[Preskitt.man]

Currently have two ASUS routers - AX88U Pro and AC88U. They are configured with Merlin as AI Mesh with the AX88U as primary. Primary servers the front of the house. The AC88U serves the back of the house and that's where the media devices - all of which are in close proxity to the AC88U and my wife's computer and kitchen TV which are the in the nether reaches of the house. The get a signal which is not horrible, but not stellar either. We also use WiFi calling which is problematical when in proximity to this area of the house - and my wife and her phone are back there a lot.
Plan A is simply to replace the AC88U (the one one in the rear of the house) with an AX88U Pro. I expect that would resolve most of the problems. It is about a $200 solution.
Plan B is free. Our internet is provided by Zona Wyrred - a fiber to the premise solution. The AX88U is connected to Zona. Zona offers at no cost - no purchase, no rental) an AXE gateway. They won't say the brand but I think it is the same or similar to the Comcase AXE gateway - kind of a tall rectangular box. So plan, would be to take that and make it the primary router and move the AX88U ot the back of the house (where the AC88U currently is) and set it up on AP mode. Figure, it if solves the issues great and if not, go back to Plan A. Only cost of Plan B is time and effort to reconfigure to set it up (and reconfigure and setup again if it doesn't work satisfactorily.

Is my reasoning faulty?

 

[Tech9]

The free ISP gateway will come stripped down to bare minimum features. It will probably have weaker than RT-AX88U Pro Wi-Fi as well. The better option is to get another RT-AX88U Pro. This way you can use all Asuswrt features plus you don't have to reconfigure your main router. AiMesh works best with identical units and wired. You are almost there, just need another RT-AX88U Pro unit and 10min time to add it as AiMesh node.

 

[Preskitt.man]

Yeah, I had similar thoughts, but thought maybe it would be worth a try. Thanks.

 

[Tech9]

U can’t run a wired connection from the main router to the second one?

Seems like @Preskitt.man already has a wire to the second location.

 

[Tech9]

He does not mention wired backhaul anywhere

Here:

and set it up on AP mode

AP Mode is wired only.

 

[Preskitt.man]

I have a wired connection from primary to secondary. Prior to my AI setup, I had the 2ndary set up a wired AP.