Internet drops randomly and comes back up a couple minutes later; Is there an easy way for me to narrow down a home networking issue like this?

I've got an Asus RT-BE7200 router and gig cable internet. Important components are wired (my home PC, work laptop, video game consoles). Plenty of stuff on wireless (phones, Nest thermostat, other devices).

We started getting drop-offs where the internet would just STOP for a couple minutes and come back. It's enough to knock me off meetings, knock us out of games, etc. We were more or less good for years and started seeing issues in the last year.

I'm trying to narrow down the issue — but don't know if there's a good "run this and it'll narrow it down" option.

Trying to remember anything else in case there's just a magic bullet one of you will say "that's the thing": I've got UPnP on for gaming. I'm on Cloudflare (free) DNS. I've got a cat6 cable in my ceiling from the router to a Netgear Gigabit Unmanaged Switch (to bring signal to my consoles/TV).

Is there a tool that can show me bottlenecks or issues? I know, I'm asking for a magic wand, but I kind of don't know where to start analyzing.