there is a way or plugin to see the full history of clients (device name mac ip when connecting when disconnecting) that were connected to the main 2.4/5g network?
at wlceventd.log there is limited information
I'm using Home AssistantASUSWRT Integration for "passive" scanning (underneath, it does it via SSH). Home Assistant is a beast for everything (not just) Home Automation, but you can just as easily use only this simple integration in it. It creates a Device Tracker entity for any MAC the router detects and tracks the state, IP, HostName and Last time reachable for all of those. Can be set to track unknown devices too. And because everything gets stored in the database, it can be queried in history, graphs and logs produced, pretty dashboards visualized, notifications sent, etc. etc.
If you want more details and active scanning beyond what router produces or a simple ping, there are many tools for that. I personally like Uptime Kuma as Docker container.
I didn't find anything available when I last looked. I wrote a simple script that occasionally examines the currently connected clients using "brctl showmacs" and compares with a known list. It's not perfect security but met my needs.