Need help on how to setup

So I just successfully installed openWRT on my Archer c2 , now I have another router, an archer C9 which is my main WiFi router which I couldn’t install dd-wrt on so I’ll just leave it as stock firmware.

So what I want to do is to be able to monitor the network, set up some rules like time restriction and adblock, I could not get wire guard to work so I’ll just leave it but I need to leave in place the port forwarding rule for Remote Desktop connection.

Basically I want to know if I can do something like [ISP modem=>openWRT router=>tp link router => wifi/lan to devices].
In this scenario, can I run the services like Adblock, network monitoring, port forwarding on openWRT router? What kind of settings or setup should I do to get this outcome.

Yes you could use the C9 with stock firmware as a "dumb" AP and Ethernet switch. There may be a setting in its user interface to do that as a single click. If not, the main thing that needs to be done is turn off the DHCP server. Then use only the LAN ports (in stock firmware, they bridge to each other and to wifi)-- the wan port won't be usable.

There is an OpenWrt build for Archer C9 though the wifi chips are not supported. It will work as a wired-only router. It has more memory and a lot more CPU power than the C2. The C2 at 8/64 flash/ram is barely supportable on new builds. Even the C9 being 16/128 memory will limit what you can install and run.

Hmm the WiFi range of the C2 is very limited so I would prefer to be able to use the C9 for the WiFi.